LD_PRELOAD won't be needed if the OS were built around containers / jails, instead of the weakly isolated processes and process groups.
The Unix kernel (both Linux, BSD, and Solaris) already had much of what's needed, say, 30 years ago, but nobody saw it as such a burning necessity (likely except Solaris which eventually developed Zones).
On a "normal" desktop system, you don't need containers or jails. Your programs must communicate with each other (copy paste, print screen, etc.).
But today every god damn UI program needs an internet connection to phone home and execute remote code. This is the actual problem which must be fixed.
The Unix kernel (both Linux, BSD, and Solaris) already had much of what's needed, say, 30 years ago, but nobody saw it as such a burning necessity (likely except Solaris which eventually developed Zones).