The most meaningful thing they've had recently is the cross-org shared channel thing, which is awesome when it works but still onerous to manage. That was two years ago. And it doesn't open up that many new users, it just keeps people in slack longer (good for stickiness, bad for growth).
This is the important point: because of tech monopolies it is no longer possible to compete on software quality. This is why Congress needs to break them up.
I wonder if Microsoft's Teams numbers were pumped up by it being freely included in O365 subs. "Oh you're a paying O365 customer; we'll just go ahead and count your included Teams sub as a Teams sub."
As it stands it seems to be the other way around, at least for the features we care the most about (meetings, screen sharing, voice calls).
So I think it's possible to compete on quality, but it's definitely harder as a lot of people will get by with a lower-quality offering.
From the outside, Teams (and Zooms) growth was accelerated because video conferencing became way more important. People didn’t need video conferencing pre-COVID because that would have just been a meeting. When they suddenly did, Slack wasn’t that good. My pet peeve continues to be that on Slack I cannot see someone’s screen on iOS - that one annoyance had us move to Zoom then teams.
An argument could be made that Slack was ultimately unable to compete in video by virtue of not having an army of high paid engineers to throw at the problem like MS does, but the features that Slack chose to focus on (like the WYSIWG editor) doesn’t say that to me