Does This Debunk the "Coolant Can Flow Through the Radiator Too Fast" Idea???

Exactly. And you can tell the system isn’t capable of cooling the engine by how far above thermostat opening the engine operates at.

If you have a 160 thermostat and the engine is running at 185 you need to work on the rest of the system.
Mine does, but the only time it does is after being cut off. lol