They re-write many apps every few years as part of their major design changes. These re-writes inevitably introduce lots of little bugs in uncommon workflows, and they often jettison whole features like AppleScript integration that cause real problems with users. They then spend a couple of years fixing the worst of these bugs, and things die down. Until the next UI-driven re-write.

I will admit they change and depreciate APIs like crazy, but do you have any examples of features or AppleScript being jettisoned that were not fixed? The issue that stands out to me was the once in 17 year 2019 cut-off for 32 bit apps with a lacking Quicktime X and Final Cut X, but even then the plan then was to get everything back up to snuff quickly.

I read a Gruber article recently that when Messages went Catalyst he had no issues with his AppleScript at all.