Well, now that slack has so "genuinely" welcomed microsoft as a competitor, I don't think they can turn around and argue the opposite for the same offering.

You're not required to use Teams on Office365. The anti-competitive behavior would be if you couldn't turn it off, and it had to be on due to core functionality with Office. Most people just use o365 for exchange and office apps.

Microsoft has nothing close to a monopoly in this space, so no.

It's not anticompetitive if the actual product is easy/cheap to implement (especially on Microsoft's existing infrastructure). If they can do something much cheaper than Slack can, and they can turn a profit at a much lower price point. The Slack product has a lot of delivered value for teams, but that doesn't mean that they have a right to high margins or high costs.

Lync, was the that the app whose Mac client I've never seen run without crashing shortly after startup, on multiple machines across multiple companies? That's right, I've never successfully used the Mac Lync client to send a message, despite having it installed on probably three or four machines over time.

That's not to say that Slack doesn't have a lot to worry about. But competition from Lync, or whatever the hell they call it this week, is not one of those things.

It's even more miserable that it's the de-facto standard where I'm at currently.

I tried IM and voice calls in Teams today and it's almost perfect. I honestly don't see much of a future for Skype for Business now.