Depends on what you're trying to upscale.

Well, the algorithms that make up many neural networks have existed for over 60 years. It's only recently that hardware has been able to make it happen.

AI gives it bit of marketing sprinkle to something that has been a solved problem for years.

Not true and I did say "any upscaler that's worth anything". Upscaling tech has existed at least since digital video was a thing. Pixel interpolation is the simplest and computationally easiest method. But it tends to give a slight hazy appearance.

It's actually far from a solved problem. There's a constant trade-off beyond processing power and quality. And quality can still be improved by a lot.