They bought ScreenHero and tried to integrate it. They screwed it up so bad that the ScreenHero founder quit after 4 years and has gone and rewrote it and called it Screen: https://news.ycombinator.com/item?id=22676040
Teams does it all OKish, although the channel based messaging is probably the worst part.
It's sort of wrong to look at Teams as a Slack replacement. Well, it is for who just want chat, and don't care about channel messaging.
It's pretty easy for Teams too.
I don't particularly like Teams, nor do I like Slack, but there is nothing feature-wise, today, that would make me choose Slack over Teams. Teams also plays much better with OneDrive and Outlook, obviously.
I think Slack is now a goner. They will be acquired in 5 years tops.