[cyberax]

It won't help much. Radio waves start getting too much attenuation to be useful outside the LoS around 5GHz.

That's still not a lot of spectrum. And you need to share it with other consumers (WiFi).

Then you start getting into the practicalities. You'll need to spam EVERYTHING with your access points. Can you imagine dozens of different wireless providers installing access points on every floor of every building? It's just not going to happen.