maybe, but tangled knots actually federate. you could contribute to repos on knot.ghostty.org and knot.tangled.org with the same account. no other platform permits one identity across instances.
But that requires people to buy into that no different from requiring other people to buy in to uploading to gitlab or some other alternative.
I think the key point is that it's one atproto login/did to many forges 1:N in tangled.org's "knots" network without the reliance on a single host provider/instance like GitHub/GitLab/whatever as a single point of failure.