I think you and I are saying the same thing. I'm not saying Slack makes Msft irrelevant. Just that Slack makes better UX which is why they're managing to make sales outside of IT traditional channels - because once users have the power to do it, they choose something else than what IT gives them. Same with iPhone. It got so bad that in many companies, people started using them in breach of corporate preference for official systems.
Just today I met with someone who carries two laptops for work: one that is enterprise-IT sanctioned to access internal resources and is super restricted; the other one to do actual work. How does he work with two laptops? SDcards. In 2019.
The fact that all the craptastic enterprise UX is holding on so well in terms of the $ amount indeed is the observation: enterprise services for the most part do suck. I don't think, and I didn't say, that it's always a winning commercial strategy to focus on UX when it comes to enterprise. Based on available evidence, I too would conclude that focusing on giving middle managers a power trip of control options looks like the better strategy, UX be damned.
O365 far exceed Gsuites market share and is generally better for users because most companies users still use the Outlook desktop client.
MS Teams exceeds Slacks market share. Team instant communication is a minor blip in the overall market for Enterprise software.
> Notice how all of these are associated with crappier UX.
Having configuration that adopts to compliance and regulation is UX. The U in the UX is just not the end user but the admin user.
Consumerization of IT is absolutely a thing, but not for this is for productivity apps, not enterprise grade apps - you're conflating the two.
To pretend like all of the features demanded by enterprise middle and upper management is irrelevant and unthoughtful, as another comment said, is just "typical SV think". UX to the end user is certainly becoming much more relevant in the enterprise space, it's not as black and white as you think.
(note - i'm a former SAP employee and I've certainly seen my fair share of shit)