I'm going to be honest, this post is a very long winded way to state the obvious.
Businesses already using some kind of microsoft software that get something "on top" which is "like slack!" are never going to switch.
It doesn't matter that teams is basically sharepoint+email+skype (and not, as slack is: an IRC-style chat system) and it certainly does not matter that bringing bots to the platform is eggregiously painful.
It only matters that business executives and people that have never stepped outside of the microsoft ecosystem perceive it as "being the same" and "being included".
I'm not really sure I follow. I'm a long time IRC/Slack user for personal and side projects, and my company adopted Teams a couple years ago. The core chat functionality is very comparable and we use it regularly for exactly that use case. Every team (organized or virtual) owns a Team with multiple chat channels that most use all day long for talking.
I am not implying that they are equally good - Slack has a huge advantage for power users with non-MSFT integrations and bots, but the core "channel-based chat" use case is pretty much 1:1.
For full context: teams came out during my current employment and I have not moved to another company to see it used any other place.
From my understanding; at least how it's configured for my company... A "channel" is more like a series of threads, reminiscent of a forum post per message which can be replied to. This is what I mean when I say it's like email; it's heavily thread based.
"Chats" are ad-hoc, un-ordered and will become inaccessible/removed when they cycle out of the sidebar (as in, you can have 20~ chats, the one last interacted with the longest ago will be dropped if you add a new chat).
Businesses already using some kind of microsoft software that get something "on top" which is "like slack!" are never going to switch.
It doesn't matter that teams is basically sharepoint+email+skype (and not, as slack is: an IRC-style chat system) and it certainly does not matter that bringing bots to the platform is eggregiously painful.
It only matters that business executives and people that have never stepped outside of the microsoft ecosystem perceive it as "being the same" and "being included".