Agreed on all your points about the security model. None of these things are black and white, it's more like each platform is a recipe and right now Apple is adding way too much salt to macOS.

The devastating impact isn't the plugins themselves, it's that no major creative apps are sandboxed in the Mac App Store, and the apps did invest in Apple technology stack are struggling for relevance. The devastating impact is in the lack of apps, and the problems the current apps are running into. I expect you're response will be: These apps are declining for other reasons, but I disagree and see a simple pattern: Apple had a strategy of supporting creating apps from 2000-2010 and creative apps thrived on their platforms, their policy was to work against creative apps from 2010-2020, and those apps stopped thriving. Simple cause and effect.