Mostly no. People didn't have access to the Internet so most of their computer knowledge came from books or magazines but those tended to be siloed by platform. Even a "power user" who subscribed to PC World or MacUser wouldn't know much about Amiga or Unix.

Byte was probably the most cross-platform magazine at time, and even then there were only so many pages to cover things - it ended up being mostly PC, Mac, and Unix workstations, IIRC.