There are certainly evil outcomes when potential contributors actively avoid the Linux kernel and/or other open source projects because the culture can be so hostile.
It's a double loss. It makes the code weaker and less innovative, and it makes the culture seem unappealing to outsiders.
You might not think that's significant. But how can you know what you're missing by not being more exclusive?
Consider: open source could be set up on a semi-formal apprentice/mentor basis. It could easily become a way for programmers at all levels to develop professional standing.
Code on a GitHub profile is not the same as being able to say "I worked on X and was mentored by Y and Z."
And "You're a moron, fuck off" is maybe not the best way to create a culture of collaborative support.
