You are switching the goalpost. Not only are there some "security" features that you can't disable and are of dubious actual usefulness like the system partition but they make it much harder to actually hack around the system and modify stuff as you see fit. It has also complexified the installation use of a range of software that is more annoying than it should be.
The openness and freedom to modify like an open UNIX was a major selling point, losing all that for "security" features that mostly appeal to the corporate are not great. Those features also need to be proven useful because as far as I'm concerned, it's all theory, in practice I think they are irrelevant.
The notification system is as annoying and dumb as in iOS and the nonstop "security" notification and password prompt is just a way to sell you on the biometrics usefulness; which Apple, like big morons they are, didn't implement in a FaceID way, in the place where it made the most sense to begin with: laptops/desktops. Oh, but they have a "nice", totally not useless notch.
Many of the modern Apps are ports of their iOS version, wich makes them feel almost as bad as webapps (worse if we are talking about webapps on windows) and they are in general lacking in many ways both from a feature and UI standpoint.
Apple Music is a joke of a replacement for iTunes, and I could go on and on.
The core of the system may not have changed that much (well expect your data is less and less accessible, forcibly stored in their crappy obscure iCloud folder/dbs with rarely decent exports functions) but as the article hinted very well, you don't really buy an OS, just like nobody is really buying solely an engine.
A great engine is cool and all, but you need a good car around that to make it valuable and this is exactly the same for an OS.
It used to be that macOS was a good engine with a great car around, in the form of free native apps that shipped with it or 3rd party ones. Nowadays unless you really need the benefits of design/video apps very optimized for Apple platforms it increasingly is not a great car.
Apps around the system aren't too bad but they are very meh, especially for the price you pay for the privilege (and the obsolescence problem already mentioned above).
It's not really that macOS has regressed a lot (although it has in some in the iOSification process) but also that it didn't improve a whole lot meanwhile price and other penalty factors increased a lot.
But I doubt you can see the light, you probably are too far in your faith.