Well, TRAMP was preceded by ange-ftp, which let you edit files remotely over ftp. I was using that in 1995, and I didn't get the impression then that it was brand new, so it had probably been around for a while already.
Of course, if your problem is "/usr won't mount", then it's likely that the ftp server isn't running either, so the advice still makes sense.
EDIT: Found http://www.fifi.org/doc/tramp/tramp-emacs.html which mentions that TRAMP started development in November 1998. I would have been getting that advice in late 1997 or early 1998, given when I started my Unix class at college. So the answer appears to be that the advice was actually correct at the time, but superseded sooner than I thought it was.