I think it would help users being safe.
When user gets an e-mail from unknown sender, it could contain some links to other sites and services than microsoft.com.
Sometimes user can think that he or she really should click the link but it can be phishing.
I try to make people in my company aware of danger. Unfortunately many of them can't learn how does it work, which part of link is domain and which is sub-domain.
What if Outlook, Teams and other apps highlighted which part of link is really a domain? Just like in the picture below:
If it was for example microsoft.com, Outlook could tell that this is safe link and does not redirect to dangerous sites.