Office.com redirects you to login.microsoftonline.com which isn't horribly bad, but is starting to get there. Now you have microsoft365.com and friends, too.
At least when things were login.microsoft.com you could apply the "last part is definitive" now that heuristic is pretty useless. And if you watch the actual DNS requests during a login, whew.
CDNs make it even worse, here's a few VALID requests from my DNS cache:
store-images.s-microsoft.com-c.edgekey.net
www.msftconnecttest.com
123499-ipv4v6.farm.dprodmgd103.aa-rt.sharepoint.com
download.windowsupdate.com.edgesuite.net
At least some end in apparently legitimate domains, but sheesh, that last one looks like something straight out of 2000s era scams.