There are many environments where people don’t have a choice but to maintain what is in production.

Whether or not viable alternatives exist, those alternatives don’t magically change org structure, office politics, budget, current business priorities, etc.

Bottom line: many people managing exchange don’t have the luxury of evaluating this problem in terms of alternatives.

I don’t know any that come close in functionality, configurability, and maintainability. Exchange scales from a one-person handyman to Fortune 500 without a hitch, it comes with an office suite and cloud storage space, you find specialists for it on every corner, and it mostly just works. That’s pretty hard to beat, even if I’m personally more than unhappy to be so dependent on Microsoft, a US product, and closed-source software; there’s just not much I can do about it.