Could you elaborate a bit? Do you think said "GitHub culture" is just because it's the largest platform, or more intrinsic qualities of the platform? Anecdotally I see many of the same problems elsewhere (GitLab, and even independent/self-hosted), but some things I can think of that might be more unique to GitHub are:

* The larger presence of commercial OSS projects setting a tone of "projects here are products to be marketed"

* Social media-like features encouraging popularity contests, curating a personal brand, etc.

* Both of the above leading to more users acting like you owe them something ("you're competing for my attention, right?")

I'm not 100% convinced that those or other GitHub-specific factors are primary causes of maintainer burnout, but I think it's certainly possible.