I don’t know at which point slack is better. We use both and I find teams annoying and weird but I prefer it because it is less distracting than slack. In some ways slack feels designed to keep my attention and stay engaged.
Lots of enterprise UI is like that for me, actually, including most PM software more complex than GH issues + boards. I find them extremely uncomfortable to use because I'm never confident I'm doing the right thing, or that what I'm doing is safe to do, or whether I'll be able to find the things I need again.
Slack is heading that way with some of their changes (the way drafts and threads are handled is juuuuust on the edge of putting it in that territory) but I still never feel "lost" for long, on there.