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).
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.