Oh this makes so much sense. Thanks so much for explaining. TIL it is a bad idea anyway to blindly do a git pull on the main branch since so much can be unintentionally break 
Only because of some admin settings, specifically regarding Discourse Connect. Also some REST API settings, some Plugin Settings and some specific manual user groups. We have a peculiar SSO setup in place which manages categories and user groups (+ group membership) via the REST API. Actual content as in posts and replies I do not care about at all during development which is why rake dev:populate wouldn’t help me, I assume.
No hard feelings here.