[Suppafly]

>It's likely that one box in this picture equals one "node", which serviced exactly one phone line at a time, and thus one user at a time.

Not really, plenty of BBS systems would allow several connections on one machine. It was more a limitation of the amount of modems you could cram into the box than anything having to do with the OS. Judging by the 4 stickers on each one (on the right) under the floppy drive, I'm guessing each had 4 lines.