They could... if their own messaging strategy wasn’t almost as bad as Google’s. Skype just got a top-to-bottom redesign that everyone hates, and Teams (which may or may not be the replacement for Lync, or Skype for Business, or whatever it’s called now) is like a checklist of everything terrible about Electron applications: it’s slow as molasses, uses boatloads of memory, and has no integration with the host OS. It’s actually worse than Slack, which is an impressive feat!
There’s something hilariously tragic about this being the perfect opportunity for Microsoft to deliver Google a coup-de-grace on messaging, and they can’t do it because they’re just as incompetent.