Monthly crashes are no big deal (in fact, I think, my phone crashes only once in a few months). Slight nuisance at most - e.g. if the crash corrupts Android app cache and system boots awfully long minutes, re-compiling the apps. However, I have three different mobile devices (2 phones and a tablet), from different vendors (Nokia, Acer, Samsung) that had suffered a hardware failure after some (5-8) years of use. Three dead eMMCs.
So, I'm sort of wary. It's exceptional, infrequent but happens quite unexpectedly and is very frustrating when it does. Especially if the recovery keys (which are rarely accessed by design) are lost, inaccessible (you're on the road) or misplaced.
My phone rarely crashes too, but the point is it tends to crash at the worst moments (perhaps all moments are the worst moments, when you are reliant on technology).
Using strong passwords and an auto-completing app like keepass, this is simply not an issue. I can log in from another device.
Also, reliance on mobile devices means reliance on some corporation's cellular network. Putting the control of your vital access into the hands of people who you know are not your friends and who would love to take more than just your money is never a good idea, in my opinion. When their system crashes you can't just reboot your phone to fix the problem, you can't do anything.. in fact. You have to sit and stew in the hell of your creation until their system magically comes back online. Not worth it.
Under what circumstance would that be considered normal, expected, or acceptable?
My phone just doesn't do that, and never has. Sure it crashes maybe once a month or so, but then I'm able to use it again within ~15 seconds.
I think that experience is mirrored by most people.