What is the purpose of /home on a Mac?
It predates Linux and was in NeXTStep from 1989.

Linux is not Unix and does not meet the Unix specification.

auto_home is the place where in a networked environment your home directory is mounted via NFS.

Any decently scripted process won't be affected by /home - if it is what else has it got wrong?

The Unix standard way to find your home directory is $HOME environment variable and home directories are not all of the form /home/X, in fact I have worked at places where the home directories have had different paths at their root i.e. some users had home directory /home/X  and others /user/Y