None of these discussions ever go anywhere. They will tell you that wlroots is standardizing all these things etc etc but as it stands today every compositor is at best reimplementing a subset of the features you describe. If I had enough money I would pay the Wayland people to work on something else and let the project collapse because they are constantly undermining the reasons I use Linux on the desktop.
There is a way to protect against LD_PRELOAD: use sandboxing. X11 is bad for security because it's an intentional escape around the sandbox.
The "tear it down and build something else argument" is also going nowhere, anything else you build is going to run into the same questions of how to go about implementing these features.
None of these discussions ever go anywhere. They will tell you that wlroots is standardizing all these things etc etc but as it stands today every compositor is at best reimplementing a subset of the features you describe. If I had enough money I would pay the Wayland people to work on something else and let the project collapse because they are constantly undermining the reasons I use Linux on the desktop.