system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is (Adobe) Flash so hated by browser/OS makers and why does it still continue to thrive despite (apparently) everyone discontinuing support for it?
gpt
Adobe Flash always has been an absolute nightmare. The only reason it became popular was because it was the only system available to display advanced interactive content on webpages at the time that was practical, and it stayed popular because it was the easiest platform to make content for.

Flash is just crazy inefficient, your browser might use 60mb of memory and 1% of your processor to display a complex webpage with text and images. If you tried to do the EXACT same thing in flash, you'd be using say 50% of your processing power and 500mb of memory. The other problem with flash, and this is completely ridiculous, is that only until a year or two ago flash would constantly crash, even with the most basic code being used without any bugs in that code.

Making the issue worse... everyone and their dad thought it would be a great idea to spam flash across every website, sometimes having 50+ flash programs running on the same webpage for no conceivable reason other than it "looked cool".

When you combine how mind blowingly slow flash is, with how insane of a resource hog it is (when just idling there in a tab you're not even using) with how insanely buggy it is, with how much it was abused when it had no reason to be there, flash became the pinnacle of being the absolute worst way to deliver content on the Internet.

Flash is so bad at one point you could have two tabs open, one playing a highly detailed MMO with console graphics, and the other being your dad's website with one animated button open in another tab that you're not even looking at. That one animated flash button might take up 20% of your memory and use 30% of your processing power while randomly crashing the whole browser every few hours, while you can run an entire video game in in another plug-in with a fraction of resource cost and no crashes.

Flash continues to thrive and became extremely popular because it's really easy to make content for it, but everyone hates flash because it runs content less reliably and efficiently than a Ford Pinto that is leaking gasoline and is actually on fire. 

Flash is kind of like if you made the easiest most user friendly tools to create content, and then made the process of displaying that content go through a Rube Goldberg machine for even the most basic functions.