The great majority of this discussion lacks historical perspective. The
Linux file system was derived directly from the pre-existing Unix file
systems. Unix and its tools were markedly smaller at the time, but so was
much storage. In general everything was allocated to a single file system
and the paths were simple. /usr, /local, and other file systems were
created for space expansion on small volumes, tool priority, and tool
segregation as a clued to solve problems as Unix advanced and then as Linux
arose. Merging is not really a new kludge, it is more of a return to the
original standard in response to better management of tools, executables,
and better choices for volumes. We should not see it as something outside
the Unix philosophy that breaks the standards the way systemd does, but a
return to the standards of Unix and Linux, and an attempt to keep things
simple. One thing that has never changed is it simple is more dependable.