I think of noon as the time of day when the sun is at the highest point it's going to get in the sky. Time zones are effectively a quantization error that means the clocks are usually wrong, but it's an error we all agree to so it works out practically.
But that fact doesn't change that noon is when the sun is at its highest point and our clocks necessarily include an error around when noon happens.
That's not a terribly useful utility in many contexts outside of social communication. As I said before, I don't see people using this for colloquial utility any time soon.
Hahaha, time is a social construct! Saying that our current system is not useful "outside of social communication" is like saying that food isn't useful "outside of sustenance". I mean, sure?, but that's the whole point of it.
Funnily enough, it also exists outside the needs of society. I personally find the 24-hour time system—especially with its half-synchronized, half-solar construction—to be pretty miserable to work with for personal needs. It's also pretty miserable for many professional concerns as a social construct, even if you manage to agree on using UTC. Time zones are an absolute nightmare.
But that fact doesn't change that noon is when the sun is at its highest point and our clocks necessarily include an error around when noon happens.