I don't really understand the question. Tech demonstrations are a data point, like anything else.
To take the UE5 demo as the obvious example here, do I think most actual games will have exactly that level of fidelity? No, because games will have more going on on-screen, than simply walking and flying around an environment.
But is it really interesting, as far as recalibrating my expectations for what WILL be roughly possible on next-gen consoles, and the tech that will enable it? Absolutely.
So "do I care"? Sure, I guess.