So, you'd say a company should use outside email? I would very strongly suggest that's a BAD idea. For example, when M$ sucked all our local Exchange accounts to their cloud, I understand (I'm not in that group) that this was a one-way deal. From a friend, who's a consultant, he was dealing with a client who'd let M$ do that when they went to Win10, and trying to get the email down for backups, etc, was a nightmare.
It depends if the company has a sufficient size to support a production, mission critical email service. How many engineers to you need to ensure a proper support rotation? I work mainly in the SME space and haven't seen self hosted email in over 5 years.
I will admit that the screech of the cloud brigade is often loud and incoherent but you have to choose your battles. Email is a bitch. It seems, from a techie point of view, the problem with Microsoft is that they are forcing an all or nothing approach. If you take Office365 then you must take the Azure Exchange also which means the core infra guys are pretty much left high and dry, reduced to helping people install adobe acrobat on the new Windows10.
I empathise. I've worked as an infrastructure admin and "Devops" engineer for over 10 years and now my role has been automated away by Kubernetes. Change is hard.