user8175: Every so often, I want to view a set of MOC instructions that exist in a CAD/digital format. But then, I conclude (perhaps incorrectly) that I can’t view it on my iPhone. However, maybe I could on my Mac, but only if I download some now-obsolete software, such as Lego Digital Designer (LDD). 
When this happens, my feelings of excitement turn into feeling stuck and uninspired. 
Bleh
Truth is, I have considered dabbling with CAD software as a way to play with LEGOs, but I feel uninformed and overwhelmed by the technical aspects. (I’m comfortable with computers & programming, but CAD seems like another animal.)
I’ve also noticed that CAD options can vary quite a bit and the choices can come & go from year-to-year. So, I worry that I could start down a dead end. 
Examples: 

TLG’s Design byMe service ended in 2012. 
I read online the Lego Digital Designer, while still in use by many, is no longer supported by the company.
I’ve read discussions about how certain elements/parts might be available in software X, but not in software Y. 
There are relatively new options, such as stud.io, with — presumably — new competitors getting ready to rear their head. 

I know I’m just scratching the surface here. 
This has left me wondering: Is there a good, single resource, such as a updated & maintained web page, that meets all (or most) of the following criteria?

It is a list of current & obsolete LEGO CAD software options (or authoritative recommendations), along with benefits, trade-offs, compatibility considerations, proprietary vs. open-source considerations, long-term viability, etc.
It is written for a more general audience, and not just for folks that already know a lot about MOCs and CAD software. 
It includes software options for simply viewing a set of instructions without the software that created it. 
It addresses different operating system or online/browser options, such as noting which ones are cross-platform or which are ideal for a smartphone, e.g., an iPhone. 

So, is there such a resource? Or is it just a pie-in-the-sky idea?

user56: It's certainly on-topic here - we have the following question with some answers - and hopefully we'll keep the accepted answer up to date (I updated it when Stud.io came out of beta for example):

LEGO Digital Designer Alternatives

However I don't know if it goes into enough detail for you - in which case you could either:

Offer a bounty on the question to get more indepth answers
Create a new question that references the existing one and stating that you'd specifically like the details you're after.

That said, you might still run into a bit of a pipe dream:

"It includes software options for simply viewing a set of instructions without the software that created it."

Unless someone has exported the instructions as a PDF or similar, you will probably need to have the software that created the model, or a similar one that can understand the file format.
The advantage that most of these tools have over traditional 3D tools is that they work from a parts list, and the files can therefore store just a reference to the part, it's translation and colour (see for example the LFXML format), so you'll need something installed that has the parts catalogue and can understand the file you're trying to view - thankfully many of the tools use the same base parts database, so this isn't too hard.

8175: <p>Every so often, I want to view a set of MOC instructions that exist in a CAD/digital format. But then, I conclude (perhaps incorrectly) that I can’t view it on my iPhone. However, maybe I could on my Mac, but only if I download some now-obsolete software, such as Lego Digital Designer (LDD). </p>

<p>When this happens, my feelings of excitement turn into feeling stuck and uninspired. </p>

<p><em>Bleh</em></p>

<p>Truth is, I have considered dabbling with CAD software as a way to play with LEGOs, but I feel uninformed and overwhelmed by the technical aspects. (I’m comfortable with computers &amp; programming, but CAD seems like another animal.)</p>

<p>I’ve also noticed that CAD options can vary quite a bit and the choices can come &amp; go from year-to-year. So, I worry that I could start down a dead end. </p>

<p>Examples: </p>

<ul>
<li>TLG’s Design byMe service <a href="http://ldd.lego.com/en-us/subpages/designbyme/?domainredir=designbyme.lego.com" rel="nofollow noreferrer">ended in 2012</a>. </li>
<li>I read online the Lego Digital Designer, while still in use by many, is <a href="https://www.brothers-brick.com/2016/01/21/lego-digital-designer-officially-defunded-and-unsupported-news/" rel="nofollow noreferrer">no longer supported by the company</a>.</li>
<li>I’ve read discussions about how certain elements/parts might be available in software X, but not in software Y. </li>
<li>There are relatively new options, such as <a href="http://www.stud.io" rel="nofollow noreferrer">stud.io</a>, with — presumably — new competitors getting ready to rear their head. </li>
</ul>

<p>I know I’m just scratching the surface here. </p>

<p><strong>This has left me wondering: Is there a good, single resource, such as a updated &amp; maintained web page, that meets all (or most) of the following criteria?</strong></p>

<ol>
<li>It is a list of current &amp; obsolete LEGO CAD software options (or authoritative recommendations), along with benefits, trade-offs, compatibility considerations, proprietary vs. open-source considerations, long-term viability, etc.</li>
<li>It is written for a more general audience, and not just for folks that already know a lot about MOCs and CAD software. </li>
<li>It includes software options for simply <em>viewing</em> a set of instructions without the software that created it. </li>
<li>It addresses different operating system or online/browser options, such as noting which ones are cross-platform or which are ideal for a smartphone, e.g., an iPhone. </li>
</ol>

<p>So, is there such a resource? Or is it just a pie-in-the-sky idea?</p>
 56: <p>It's certainly on-topic here - we have the following question with some answers - and hopefully we'll keep the accepted answer up to date (I updated it when Stud.io came out of beta for example):</p>

<blockquote>
  <p><a href="https://bricks.stackexchange.com/q/1867/56">LEGO Digital Designer Alternatives</a></p>
</blockquote>

<p>However I don't know if it goes into enough detail for you - in which case you could either:</p>

<ol>
<li>Offer a bounty on the question to get more indepth answers</li>
<li>Create a new question that references the existing one and stating that you'd specifically like the details you're after.</li>
</ol>

<p>That said, you might still run into a bit of a pipe dream:</p>

<blockquote>
  <p>"It includes software options for simply viewing a set of instructions without the software that created it."</p>
</blockquote>

<p>Unless someone has exported the instructions as a PDF or similar, you will probably need to have the software that created the model, or a similar one that can understand the file format.</p>

<p>The advantage that most of these tools have over traditional 3D tools is that they work from a parts list, and the files can therefore store just a reference to the part, it's translation and colour (see for example <a href="https://bricks.stackexchange.com/q/1349/56">the LFXML format</a>), so you'll need something installed that has the parts catalogue and can understand the file you're trying to view - thankfully many of the tools use the same base parts database, so this isn't too hard.</p>
