Case in point:

Take a regular road bike with both front and rear brakes. Attempt a maximum deceleration test with both front only and rear only brakes. Front brakes win every time. This is not refuteable.

This is why cars have larger rotors in the front wheels. Same with motocycles. It's a matter of physics - when stopping, forward weight transfer occurs.

To claim that one could stop better with rear brakes (let alone brakeless with a fixie) is foolish. Sure, you might be able to stop and be in control, but a brakeless fixed gear bicycle will never have the stopping power of a front brake equipped bike.