I learned to play chess in the sixties and seventies without engines. It wasn't paradise.
You would work a chess problem from Chess Review then read the error-riddled solution and wonder WTF. Likewise you would read game annotations from GMs that seemed equally dubious and be confused.
If you had complex positions in your own games, you could run around in circles forever trying to work it out and just reinforce your own mistakes. If you had a friend who was rated several hundred points higher, maybe he could set you straight, but if not, you were out of luck.
I believe its rated around 2500, and its what i used until i bought fritz 13.