As a project member, I want users to already be logged in to the bug tracker. The lack of friction, likely from being the network effect winner, is key. I know fossil has this, but people don't have their private keys in fossil, they (I) don't even have fossil installed.
Whatever happened to OpenID, anyway? That was supposed to be federated one-click login. If the problem is login, then only the login needs to be federated, and this approach leaves the rest of the system more flexible as sites can have different bug tracking features without becoming incompatible with the federation.
Apparently there are two competing ID federation setups, and a bunch of "login with Google/Apple/Facebook/ID.me" and nobody can agree on anything.