So I think it is core to the way Microsoft expands and holds market share. And that market has changed to not only want windows only tools, so they change with it. Microsoft culture has always been kind of pragmatic. They were a walled garden for developers when they could get away with it (and still are for some), but now they have opened up a bit out of need.
Microsoft is a different beast because so much of their revenue is B2B. Continuity of operations is kind of their whole deal. Google Workspace is the equivalent Google product and they're much less likely to dump a service, unlike the rest of Google.
There's also some pretty decent integration features for DevOps projects with source control in GitHub for that matter iirc. Not to mention the potential upsell to/from GH Enterprise and/or Azure DevOps.
I can imagine at some point, GH Enterprise and Azure DevOps may become more similar and share more infrastructure over time.