It is. Most new Microsoft apps are web apps. Though they're ditching electron for some better web wrappers.

They're also beginning the process of passing 365/Enterprise Outlook for this new watered down Outlook. Enterprise users are obviously pissed to see "Try the new outlook!" hovering over their regular outlook like a cloud of doom.

The outlook subreddit made a gigantic list of feature imparity. Microsoft has made some feature progress since then in preview. But it'll suck when they actually release it I'm sure.