The partitions that get updating are completely separate from user data. This myth keeps spreading for some reason though...
The only time user data gets wiped is when unlocking the bootloader which is a very valid security feature in order to prevent bootkits and data theft. It gives big clear warnings to backup your data before doing so.
Mine Samsung S4 mini reboots by itself once in a few days. Hadn't bothered to catch the reasons. And it surely knows how to hang itself for half a minute when doing large app updates or otherwise IO-heavy operations.
A limited functionality device that services a specific purpose, if we were to take it to the world of the web, would be a webservice.
If you were having a problem with one of your puppet&co managed web servers on some cloud host, would you: a. perform root cause analysis. b. redeploy the entire machine because fuck it, you have your recipes or whatever and spinning up a new instance is a super cheap operation.
That's what I read into when I think about the grandparent.
Low maintenance partially because they are functionally very limited ( much of what the kernel and userspace can do is locked-out) and partially because the mission-critical stuff lives in seldom-updated firmware.
High availability... Given how often 'reboot your phone' or ' clear the app data' is given as advice?
I just don't see many parallels with server environments.