One factor (surprisingly I've seen this mentioned by a video game guy on youtube few years ago) is the disbelief made by non game visual art. Game boxes, booklets, they bootstraped the imagination. Handmade art was 100x more detailed than 8bit games yet we didn't care having a low res 8bit characters because we were already mentally in the world displayed on paper.
I do sincerly miss the limited rendering aspect of old titles. The limitations gave ways to a distinct style, and kept the game a game, in a strange world. It also provided you with some surprises.. how did they manage to pull off some effect on a tiny 8 or 16bit machine. Hardware of today removes that wonder. There's less contrast.
The limitations of old game platforms didn't vanish, they are still used (and being re-discovered by new generations). One of my favorite games on this side of the new millennium is Celeste, for example.
Some indie studios are even producing new games for GBA, GB, NES and other platforms from the 90s, sometimes including booklet and packaging!
I assume you mean the suspension of disbelief? I.e. immersion. Suspension is a key word there, as in, your disbelief is halted, allowing you to be immersed.