Yeah, outlook - in all its variants - is awful in Windows (in all of its variants). But there is another outlook that is even worse.
Namely, outlook for iOS. I've been forced to use this (along with outlook for windows on my work laptop) for years and it never gets better. It generally gets at least one update a week from Microsoft to patch the various security holes that are constantly being found.
What's so awful? We can start with the terrible search system. We can continue on with the completely arbitrary - and non-configurable - way that it decides which messages to keep offline for reading and searching when you're disconnected.
But those aren't nearly the worst. The worst has been around for a long time and there is no sign of them ever intending to change it. The worst problem with outlook for iOS is - strangely enough - not present in outlook for windows. The worst problem with outlook for iOS is that the default reply action is always reply all. This doesn't sound awful at first but if you work for a giant corporation of 10,000+ employees it can quickly become disastrous. An announcement to the company triggers an avalanche of replies that flood mail boxes around the world.
Being as no patch has ever changed this over the years it must be assumed that Microsoft sees this as "a feature and not a bug". Can we change the behavior on each device? Probably, but there is no way to roll that out throughout our enterprise.