I don't remember reading any of the manuals of any of the games I played as a kid in the 80s. I don't even remember seeing them. I just remember putting the game in the console as quickly as possible and figuring it out.
Some games weren't intuitive, or had various power-ups and items that weren't obvious. Most of the manuals for the Sega Master System and Genesis games were just a few pages, so it only took a minute to read them. (And then there were the RPGs...)
I remember getting charged $3 every time I returned a rented game without the manual.
Haha. I completely forgot that game rentals came with a manual. I remember them always being absolutely beat up, and near shredded, but usually there!