There has been a pattern for like 40 years of updated Mac OS breaking older software. I think it involves their approach to adding new features. I understand breaking software that makes use of undocumented features in software, that used to be common with Windows. It actually amazes me as to how much of my old software still works with Windows 10, even though Adobe doesn't. Lots of my old 1980's DOS software doesn't work any longer, there has been too many hardware changes. I keep a old pc that runs DOS for cases where I actually need to run some old stuff.