O365 and the product integration there (teams) is why they crushed slack despite slack’s headstart. Slack sold out to languish at salesforce while Microsoft will now just own that space.
Cherry picking a Microsoft app for macOS is like looking at iTunes on windows, it’s not really representative. Even Windows itself isn’t that important (that was one of the big strategic changes after Ballmer left and Nadella took over). You’re right about edge though (which is why Microsoft abandoned it for WebKit).
Microsoft also ships (something Google can’t do very well). I think their current trajectory is probably undervalued because people have not properly updated from outdated historical sentiment.