Ahh, but it's not just super fast.
It's something that can actually be used to define the game around it. Much like the Cell was, and the Emotion Engine before it. For the best use of the architecture, it'll need teams to actually use it for more than quick loading times. It's like Nintendo do when they introduced mainstream motion controls, or dual screens, or 3D screens. Their own teams come up with creative game changing uses, whilst others don't. Those latter results are still cool, but forgotten past the initial buzz.
But you are correct, multi games will restrict the PS5 to the lowest common denominator in some regards, just like the PC always has been. But that's not to say the XsX nor the PC can't be fast still, let's remember the PS5 has a new pipeline but it's still not hugely powerful in other areas, so balance will inevitably come.
BTW the best thing about that Ratchet game, and like the little devil inside one, isn't the level loading tricks. I loved the particles, the grass and the art style and the engines behind them. They showed that beyond all the usual nonsense of "x times more powerful!" and all the fluff of bigger textures and more polys, that the true beauty can be in the scenes themselves and how much more effort we will see in shaders, effects and lighting. Also, the Ratchet demo was super smooth in terms of framerate, people who argue "30fps is enough!" really don't get just how good a constant 60 actually is. And even then, that's years out of date