I was wondering about that too... According to the spec:

/home is a fairly standard concept, but it is clearly a site-specific filesystem. The setup will differ from host to host. Therefore, no program should assume any specific location for a home directory, rather it should query for it.

Sometimes home directories are in other locations. My University used to have different mount points for different graduating classes on our Unix servers. And I use "/home2" for one of my servers for... reasons.

Though I'm not sure that qualifies as "deprecated"? I get the "non-standard" bit though.