They're already doing that by moving discussions to issues. In fact it's more work for them because they have to actually create the issue instead of just adding a "confirmed bug" label or whatever.

I guess it probably leads to higher quality issue descriptions at least, but otherwise this seems pretty dumb and user-hostile.

There’s a one-click button to convert from discussion to issue (and vice versa). It’s hardly more work. But I do feel like discussions are kind of hidden and out of the way on GitHub.

On repos I maintain, I use an “untriaged” label for issues and I convert questions to discussions at issue triage time.