Using classic Outlook for Windows in business environments
This issue is certainly frustrating, and I'm seeing the exact same thing I see at my job, development and support outsourced and fixes, even to stuff far more critical, take weeks or even months to fix.
That being said, it has not been "down". Webmail (accessible via phone browser) has been fine, albeit inconvenient, and bouncing network or cancelling password prompts has worked for most.
They need to fix it, they need to roll back whatever they did, but honestly even with 49 pages of comments here, my guess is the impact is to a small percentage of their user base. Large corporate clients are their main concern, and only ones that aren't using modern auth correctly (which has been required since last year) seem to be impacted, at least from what I've seen here.
I guess it is a good illustration of how reliant people are on email as a primary means of communication, and they forget that there is good old fashioned talking to the other person.
Had email for work been down for even a few days and people were missing customer meetings, the only people facing termination would be those responsible for the email infrastructure. The rest of us would have found a workaround, even if it came down to writing on a physical calendar (but I'm confident they'd find a better workaround like telling us to stay logged into webmail and web Teams).