Gitlab is a great product but using it has a negative effect on getting contributions for an open source project outside of the core developers due to Github's larger user base. I have seen this play out many times.
It might mean less bug reports from users who find bugs, but aren't deeply affected by them.
The upside is a lot less garbage in your issue tracker.
OpenID was supposed to fix a lot of problems and doesn't appear to have, at all.
Anyway, there are lots of people who are not only knowledgeable enough but also skilled enough to triage bugs, but don't want to go through the rigamarole of a new account, e-mail, clicking a verification link, reading the bug report guidelines, etc.
Putting walls up to contribution is indeed a good way to get fewer people contributing. There's no guarantee the ones stubborn enough to still report bugs are reporting any better, though.