That's a step back, Github and Gitlab did lower the barrier of accessing and then getting started to contribute to open source.
The old days is not that good. Mailing lists solve the problem of group communication, but with a twisting mental model. In my opinion, email should just be for announcements, doing public communication by email is like writing embedded software in JS, it works, but not great. Another fuss, we can't modify email that has been sent, it let people think more before posting, but people will be more afraid of posting. Forum is just better for every communication.
Bugzilla is ugly. I think issue tracker should just be a git repo with hooks to enforce its integrity. Then we can have many front-ends for it (GUI, CLI, web).
Github and Gitlab glue things up, they work on integrations so we developer have better experience, that's why we use them
GitLab, Gogs, and Gitea are all self-hostable and offer the same tools that GitHub does, if it's the convenient packaging you're after.
Sourcehut can also be self-hosted but they promote a mailing list based workflow, which I think is less of a problem than you make it out to be but then we don't have to agree on this point either :) That's the beauty of FOSS, we're free to choose for ourselves.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.