Companies stick with it because of Exchange. Office 365 means Microsoft gets to manage email problems in return for money.

Everything else comes along for the ride.

We spend probably 20 hours every month on the phone with them managing various issues. My CEO has asked if we could run our own email server and I have refused every single time for the simple reason that we would now spend 40 hours per month on the same email issues since both source and destination of the complaint would be company internal.

AND we would be fighting getting our email delivered because Google and Microsoft basically dump your email in the trash for not coming from Microsoft or Google.

No thanks. Pay Microsoft. They're the least bad in the space.

Office 365 is completely new and different.

If you’re ok with the apps, then it provides a ton of value for a fraction of the price others do.

I mean, Slack itself is almost as expensive as O365 which offers Office (online and offline) and a ton of other apps and features in addition to Teams.

There are more workers than software developers. Specialised version of Word and Excel are literally provided in the CPA exam. The general concept of having an integrated "suite" of office software compatible with eachother, G-suite or o365, is also very appealing.

What is obvious is no single person requires all of it, and everyone uses a different subset of features so its nice to have everything in one package. The integration with their admin cloud service allows easy management of the software in terms of deployment, compliance and everything else. I agree it is bloated and there is significant vendor lock-in from MS, but there is nothing comparable IMHO. I think it would easily cost $100 mil to duplicate all the features.