Most recruiters don't their ... from their ... (fill in the blanks).

Most hiring managers at bigcorps aren't nearly so clueless, but a lot of them take a, how to put this, long-term view of things... and don't always know about from GitHub or SO, let alone what cachet they have in hacker communities.

So again, it can be a, let's not say perfectly viable, but viable-ish strategy to bank on one's commit history on GitHub, and other proxies like Stack Overflow... if you're content, and secure enough in your market value to stick to the 5% of the employers that value these kinds of markers very greatly.

But for the other 95%, not so much.