Linus actually commented on this lack of identity handling in 2012 in his famous explanation of why he doesn't use GitHub: https://github.com/torvalds/linux/pull/17
"since github identities are random, I expect the pull request to be a signed tag, so that I can verify the identity of the person in question."
And:
"github throws away all the relevant information, like having even a valid email address for the person asking me to pull."