Frankly, I have a hard time believing that the misanthropic commenters on r/programming are major opensource contributors. The most prolific programmers simply don't have time to waste on comment threads.
"Of course, I'd also suggest that whoever was the genius who thought it was a good idea to read things ONE F★CKING BYTE AT A TIME with system calls for each byte should be retroactively aborted. Who the f★ck does idiotic things like that? How did they not die as babies, considering that they were likely too stupid to find a tit to suck on?"
- Linus Torvalds, principal author of the Linux kernel
Linus was speaking abusively there, but he wasn't just speaking abusively: there was a context. That context wasn't that Linus spends hours every week trolling Reddit by putting people down and making snarky remarks about every new project. The comparison to Linus is really irrelevant and needs to stop.
Probably because the things they do aren't up to scrutiny. You don't know it's bad until someone/something comes along and tells you, or you just happen to discover a better way on your own (that someone else has probably already discovered). The computer doesn't shock you if you write terrible code, after all.
Perhaps the best part of some jokes is that half of the monkey people take these exaggerated fictions seriously and become quite upset upon processing them. This is in itself also a joke.
I pulled back from the community around some of the stuff I use for much the same reason, it's the same people telling other people they are "doing it wrong" and yet almost without fail those people aren't doing anything interesting.
The ones I still respect don't say a real lot but either have amazing blogs full of interesting stuff or repo's full of interesting and useful projects.
As my grandfather used to say "don't tell me I'm wrong, show me".