Well, I'm not disagreeing with you, at least not precisely, but you very well may be in a way.
You, based on all appearances, are very consistent in how you configure a multitude of things across all your MSP clients. I would imagine that other MSPs are, too. But, and here's the big but, you may be doing "everything right" and they are doing "one small thing wrong," where that one small thing is at the root of all the issues.
I have said, repeatedly, that very few problems/bugs are truly global. The rare ones that are affect each and every user who has occasion to have Windows follow a given code path (and, even then, you could argue that not everyone will ever follow a given code path). But most problems are idiosyncratic to something directly related to the Windows installation on a given machine.
So, if you take that "on a single machine" idea, and recognize that it can be widely propagated via MSP standardization, it's entirely possible for a very great many people to be hit by something and others not.
But, after all the above, I'm with you. The amount of electrons that have been spilled about this seems grossly out of proportion to the number of users actually affected, and it's nowhere near to all users who applied the so-called demon update. There absolutely has to be "a certain something" present on those machines that cause the system, after the update, to "trip up" that is absent on many others.