I guess that OP is referring to teams having this builettin-board style posts as a default. You post a post and others can react and comment. Which works like a mashup of old school forum and chat. It breaks chronology as newest updates are not on bottom or top.

It was even called teams. So teams had a special use section called... teams. They recently changed the logic. Chats and teams are in the same place, but the rest is still a thing.

I don't think there is a way to notify a chat. Like on slack or zoom or whatever. You can make a webhook to teams (ekhm, the post board thing), but not a chat. So you basically can't use Teams to make many small notifications because you just can't show them next to each other - it's always a big post.

My favorite "feature" of teams is the missclicks. If you use it folded, when chat list (or teams list...) autohides, some parts of the list takes to the chat you want, but some...click the element that was beneath whatever you clicked.

So you wanted to change a chat to some 1:1 with a friend, but you clicked some OneNote in a group chat.