Honestly, O365 is very poorly designed and operated product - I've seen countless organisations either implement it from scratch or migrate to it and they've had more problems than they can afford - the amount of undocumented downtime over the last year has be absolutely unbelievable - If i told you how many clients have said they have not weekly - but daily problems you wouldn't believe me.

Bundle that with cleaverly designed vendor lockin and General poor UX and you've got yourself a real headache.