In my youth I purchased a second hand C64 it came with around 300 games and a disc drive but also a tape drive with a number of tapes,since the tapes had some games not on my discs I tried the tape drive, it took around ten minutes to load a game into the 64K memory the vast majority games loaded fully into memory. some worked in a similar way to future games with multiple discs,where the game stopped and you manually loaded another tape went and had a bath made a cup of coffee walked the dog and then continued the game, asset loading came much later mainly due to HD's
Ah. So once you load the came the cassette no longer needs to be read. I get it. Doesn't seem like a great system but I imagine it was cheaper than cartridges.