Some of the biggest changes in gaming engines is that they have gotten much much more advanced about streaming first low res assets in, starting the game, then continuing to stream high res assets in on the fly.

Even if a user doesnt have cached assets (which i think is the main point against your supposition, that assets can be cached after first launch), ideally a modern game could still load very fast at very low fidelity & keep pulling down higher fidelity assets as the user plays.