Re: GitHub > GitLab
Judge for yourself: just compare the GitHub help with the GitLab help.
Most of what you wrote is about git, not GitHub/GitLab, so is equally true of both. Both also have wikis, although I don't know how they compare.
It's not clear what your point is regarding the help. IMHO some parts of GitLab's help aren't great (to put it mildly), but I've suffered far worse.