it's like the first person invent a way to make the pop cap for your travel coffee mug. Like, anyone could have come up with that idea, right? compare to screw cap we used to have. We do have plenty of examples where the patent aren't really popular until after it is expired or irrelevant.
Like, yeah, in a heatlhy competition env, it is way better for consumer in the beginning. But because of how capital works, eventually without patent it all goes to the bigger corps.
The Namco(which I wrongly attribute to Konami) thing "is" very specific. Remember during that time there are not a lot multi core processors. It requires clever scheduling to allow running both the mini-game AND checking loading status to seamlessly transition into game. It's really not just a simple "concept" but ingenuity to arrange your loading I/O wait time into running their past game at the same time. That's in PS1 era where loading wait time because of CD-ROM and later DVD was very significant.