user53202: I saw an answer to a question on this site, which I found difficult to read, due to the author not having split the text in to proper sections.
So I simply added the paragraphs, where it made sense. But was unable to save the change, since the change was less than 6 characters long. This tricked me, because the change was a real improvement to readability. The content was actually fine, so I did not want to alter the wording only the readability of the post. 
Why prevent people from doing that?

user24613: It only applies to peer-reviewed edits.  Once you reach the edit posts threshold (2,000), you can make edits of any size, and you don't need an edit summary.
It's almost definitely a measure to prevent people from loading the queues (which are already loaded enough on some sites) with tiny edits.
The best practice (and one I do fairly frequently) is on sites where you're under 2k, simply drop a comment to the OP mentioning the issue.  90% of the time they edit it themselves.  Just keep an eye on the post so you can remove the comment once it's done.
See this post from Jeff Atwood and the links Bryan Krause shared for more info.

53202: <p>I saw an answer to a question on this site, which I found difficult to read, due to the author not having split the text in to proper sections.</p>

<p>So I simply added the paragraphs, where it made sense. But was unable to save the change, since the change was less than 6 characters long. This tricked me, because the change was a real improvement to readability. The content was actually fine, so I did not want to alter the wording only the readability of the post. </p>

<p>Why prevent people from doing that?</p>
 24613: <p>It only applies to peer-reviewed edits.  Once you reach the edit posts threshold (2,000), you can make edits of any size, and you don't need an edit summary.</p>

<p>It's almost definitely a measure to prevent people from loading the queues (which are already loaded enough on some sites) with tiny edits.</p>

<p>The best practice (and one I do fairly frequently) is on sites where you're under 2k, simply drop a comment to the OP mentioning the issue.  90% of the time they edit it themselves.  Just keep an eye on the post so you can remove the comment once it's done.</p>

<p>See <a href="https://meta.stackexchange.com/a/77257/372269">this post</a> from Jeff Atwood and the links Bryan Krause shared for more info.</p>
