But that is already true. You cannot buy a mac any more which runs 32 bit software. So Apple is obviously willing to make things miserable for a considerably part of their user base. Me included. I will avoid anything with Catalina, because I still have a very few 32bit programs I want to run and can't upgrade. As long as macOS runs on x86 hardware, there is not much justification for such a break. Yes, they clean up the software stack, but at a very high price.
The only good reason I can imagine is, that when Tim Cook announces macOS on ARM, he will claim "runs everything that runs on Catalina".
Doesn’t that invalidate your earlier claim that “it wasn't very bad and most developers complied, which is an argument in favour of an ARM transition being feasible”? It doesn’t matter how nice the experience is for those who upgrade if a significant number of people avoid upgrading because the experience would be terrible. That’s selection bias.
Sure, Coke sales are down 50%, but the customers who are buying New Coke say they like it just as much as the old recipe!
Which earlier claim of mine? Are you mistaking me for another poster?
My point was, that they already had the breaking change so the change for the Catalina users - which certainly is only a part of the Mac users, many stayed on Mojave because of the 32bit support - will be smooth.
Not sure what you mean by "diverse". There is a lot of legit macOS software, which is 32 bit only and no longer updated - for example because the company went out of business or couldn't justify the effort for a port. Cutting support off for these programs is a harsh step. While I can understand that Apple doesn't want infinite backwards compatibility, it hits a lot of users. One reason for this might be the preparation for the bigger switch to a new cpu architecture.
The only good reason I can imagine is, that when Tim Cook announces macOS on ARM, he will claim "runs everything that runs on Catalina".