Knocking and engine efficiency are inter-related.

That being said, unless you are constantly flooring the accelerator and / or doing a lot of track driving, it seems challenging to make a modern (and properly functioning) engine knock on a persistent basis (irrespective of octane).

This is a weird hill to die on man. Modern ECUs are smart enough to tune the timings in to prevent knock when the wrong fuel is used, at the cost of both efficiency and fuel economy. "Runs" is not the same thing as "runs well"

Are you familiar with Boyle's Law? You compress a gas and it heats? Higher compression of air/fuel lowers the detonation point. If your air/fuel mixture detonates at the wrong time in an engine, you will get damage. Higher octane fuels take higher temperatures to detonate.

That's why higher compression engines REQUIRE higher octane fuel, as the manufacturer will specify. Run without it, damage your engine and try to make a warranty claim. Good luck with that!