I can't tell if you're being intentionally dense or just naive.

Linus copied the kernel tree to GitHub when the kernel git repo was compromised. It is not the main repo. Of the others, only Rails and JQuery could even be reasonably be called "top" projects (Bootstrap? Seriously, you list a 7 month old project with 2000 commits?) and even those are a stretch. Major projects are well into the hundreds of thousands of commits. It's ludicrous to even muse of Bootstrap being in the same league as e.g. Mozilla, WebKit, et al.