Most of this reasons also are not "locking down" reasons. 32 bit mac Machines or PowerPC did not stop working - there are just no OS or modern App updates anymore. This support anything till the stone age syndrome in Windows is one of the big problems why Windows is such a big pile of mud. If you need to support something old in macOS, you can use virtualization.
Yes you can choose a dozen mediocre UIs on Linux and every App developer has to decide for which he writes his app. It shows. The "year of the linux desktop" is still the unicorn that maybe never appears. "Desktop PCs" still are either running Windows or Mac.
You can't change UI or the Kernel in Windows and NTFS is not open source either.
The purpose of operating systems is changing. The OS platforms are more and more unimportant. People's computing life is more and more within some browser window and it is more and more unimportant on what platform this browser runs. macOS was and is a good target for running OpenSource software. Windows got better for that - at least since the WSL, but its still easier to compile for macOS most of the time. Even then - development has shifted to virtualization and containerization - which works on macOS too.
There are reasons why running M1 macs today may make your life more difficult, but most of your reasons seem to be fabricated a bit.