Here's a little bit of the history:

http://lists.busybox.net/pipermail/busybox/2010-December/074...

When the operating system grew too big to fit on the first RK05 disk pack (their root filesystem) they let it leak into the second one, which is where all the user home directories lived (which is why the mount was called /usr). They replicated all the OS directories under there (/bin, /sbin, /lib, /tmp...) and wrote files to those new directories because their original disk was out of space. When they got a third disk, they mounted it on /home and relocated all the user directories to there so the OS could consume all the space on both disks and grow to THREE WHOLE MEGABYTES (ooooh!).

It's long been variable between UNIX versions and variants, for example Solaris 5.x (which is a descendent of AT&T UNIX shown in this video), the common location was/is /export/home, since home directories were commonly exported via NFS to other machines. It might have been IRIX from memory that even used /usr/people.

VFS was introduced around SVR4 as part of the SVR3/SunOS merge IIRC so that made it easier to mount home at whatever location most suited, but the reality already was that home was wherever your /etc/passwd entry said it was. Most Linux distributors had de facto standardised on /home long before the Linux FHS.

Looking at more recent BSD's, FreeBSD 11 seems to be using /usr/home, with both OpenBSD 6.x and NetBSD 8.x using /home by default.