One contributes to GH is more-often tech or projects you're interest in, whilst a resume is going to be the alphabet soup of all tech you know.

HN is doing a good job of complaining about all the edge cases where this won't work because most of us don't contribute high-quality, novel work to GH. For example, for me, my recent GH contributions are for an ancient video game in a niche language I've never used elsewhere and my location isn't even exposed. So I won't show up. Boo hoo.

It's still a neat idea.