I think he meant just the network effects of a social platform. Github has more people in them so there are more people interacting with repositories hosted on Github.

I wish that somehow people carried identity across Github / Gitlab / Gitea / other services. Like, a federated issue tracker. Or otherwise that the issues themselves were easily movable between platforms, with no lock-in. But the incumbent platforms rarely want something like this.

An alternative is to eschew platform issues entirely, and use decentralized issue comments hosted as Git repositories, like https://github.com/dspinellis/git-issue or https://github.com/neithernut/git-dit or https://github.com/MichaelMure/git-bug - I think that Gitlab should offer integration with one of them. I mean: both allowing to export issues and PRs into a Git branch, and allowing people to comment on issues and PRs by pushing to a Git branch.