Pretty easy to describe, even at the time, since that was the Unix Way since...the 1980s. NeXT invented none of that. Pretty much anyone who went to a top engineering school in the late 1980s or 1990s had this single sign on, cluster experience (e.g. MIT Athena, whatever CMU had, etc.).
> I walk up to any of them and log in as myself. It goes over the network, finds my home directory on the server, and it just, i've got my stuff, where ever I am. And none of that is on a local hard disk.
You can do all of this with NIS and NFS (and, in-fact, NeXT did. In NeXTStep, NIS (aka YP) was known as NetInfo.