Well in an immutable distro, there is little to no chance for the system to end up in an unusable state (I guess it is the same for distros which apply the updates atomically). Traditional distros are far more likely to bork when so much shit is updated at once
I don’t think this is true. The package manager is there for a reason to prevent that. If you have more updates to install at a time, then the chances are the same as if you would have installed the problematic update one at a time. Just read the manual intervention information from Arch and see if there is something to do, then it won’t bork. If people don’t know what they are doing and do not read the additional information (that is required to do so on Arch), well yes, then you could end up borking your machine. But not because so many updates are installed at a time. The package manager and operating system and their maintainer designed it in a way that you can install ton of updates at a time without borking. This is fine.
Between this comment about arch and the other comment about opensuse, it must only be apt which has issues with large updates with complicated dependency chains. I remember 5-6 years ago Ubuntu borking itself when I tried to update after a decent gap and had 100+ packages to update. There is also the fact that people used to advice me to make a clean install in lieu of updating whenever a new version of Ubuntu dropped.
