[blep-arsh]

Not every computer is a part of managed corporate inventory. And some suppliers will happily ignore any issues their updates are causing. E.g. forced Windows feature updates can just disable a computer by throwing out essential but unsigned drivers.

[Klaus23]

This is more of a technical problem. If your update either breaks something or leaves gaping security holes, then there is no good solution. I think I would rather inconvenience a customer by turning off functionality than leave a bad vulnerability unpatched, but delay an update if it is not security related.