Exactly - that's what I was trying point out in my original comment. The desktop office apps are actually reasonably easy to swap out for a large portion of people. It's the rest of the M365 suite which is massive.
and, its so cheap. there are alternatives for individual components, but nothing that comes close to being this low cost. And, the ultimate value is that if you buy a niche tool (like notion) then only people with licenses can use it. Everybody at the company has office, so it's easy to share/collaborate. You have to really commit to avoiding office at all if you're going to replace parts of it.
Cheap is the same reason I ended up on an M365 family plan before they stopped allowing custom email domains. I'm grandfathered in, but I will probably end up paying more for just email when they decide to cancel the feature, plus needing to find a place to stash my off site backups.