Adding that check to every incoming comment in a large scale system and adding the previously nonexistent interactive UI for it is far from “super easy”. This is not a Todo MVC. There must be a thousand higher impact stories that are better targets of engineering time (unless this form of trolling become a new pastime).

In addition, there are lots of actually malicious skids you can’t stop by asking nicely.

Or: show ‘x users’ behind the @group in a greyish label.

Teams can be secret. This might be a secret team to begin with? Anyway, I highly doubt they deleted the team since it’s used as an authorization mechanism.

It's "secret". You need to be in it to see it.

The team is still there, only members can see it.