I think it's not that you don't understand the problem, just that you haven't experienced it.
My Windows 10 machine installs updates that require reboots more than 2 or 3 times a year, but it is configured (and I believed this is the default) to install them and reboot at night, when no-one is using the computer.
So when all goes well, I hardly ever see the computer install an update or reboot because of it: normally this happens when I'm not using it. But last year it got stuck in a cycle of trying to install an update, failing, uninstalling and trying again later. Each attempt took about 15 minutes and required, if I remember correctly, two reboots: one after the attempted installation and one after uninstalling the update. It tried so many times! It seemed to want to try more when I actually needed the computer for something work-related. :)
After trying a bunch of things I found in forums (it seems like it is a very common problem), none of which solved the problem, I reinstalled Windows 10. It's back to normal, updating at night, but I know at any moment Microsoft can screw up another update.
> it got stuck in a cycle of trying to install an update, failing, uninstalling and trying again later
To me, this is one of the biggest issues with Windows Update: it's unreliability. When an update doesn't install, there's no reliable way to get it to work without shutting down services and deleting the updates folder; all technical tasks that most users don't know how to do.
I'm on insider updates and this happens occasionally on builds, but most of the time the updates apply just fine.
> the biggest issues with Windows Update: it's unreliability
I have the same experience, and i always took this for granted... but after i bought a Macbook i learned there are actually operating systems where updating is flawless.
My Windows 10 machine installs updates that require reboots more than 2 or 3 times a year, but it is configured (and I believed this is the default) to install them and reboot at night, when no-one is using the computer.
So when all goes well, I hardly ever see the computer install an update or reboot because of it: normally this happens when I'm not using it. But last year it got stuck in a cycle of trying to install an update, failing, uninstalling and trying again later. Each attempt took about 15 minutes and required, if I remember correctly, two reboots: one after the attempted installation and one after uninstalling the update. It tried so many times! It seemed to want to try more when I actually needed the computer for something work-related. :)
After trying a bunch of things I found in forums (it seems like it is a very common problem), none of which solved the problem, I reinstalled Windows 10. It's back to normal, updating at night, but I know at any moment Microsoft can screw up another update.