I'd have to ask my corporate IT, but I understand that if you perform enough unholy rituals to bind Exchange and SharePoint and AD together, everything somehow becomes smoothly accessible from everything else.

Like, e.g., hovering over someone's profile on Teams is the quickest way for me to check if they're on a leave and have auto-responder set for their e-mail. Or, calendars staying in sync, and Teams automatically applying a "Busy/DND" status based on your "busy" blocks. Or, from the more annoying side, how Yammer (Microsoft's pseudo-Facebook for Work) updates pop up in both Teams and Outlook. Or how the same files you exchange inside teams in Teams can also be found via SharePoint, and even pop up in Outlook. Etc. There's a lot of those tiny things.