Slightly pedantic here, but I'm pretty sure Ian, Mikey or myself could out brake a fixie. Assuming sufficient grip on the road, the limiting factor in rate of rider deceleration quickly becomes the physics of staying *with* the bike. On a diamond frame, the rider is perched on top and will struggle to get their weight far enough behind the front wheel to really take advantage.
On a 'bent, the bulk of rider mass is well behind the front wheel, and typically far closer to the ground. At the point where most DFs would be carried forward over the bars, the bent will keep on stopping.
Personally, I don't know how you lot keep your balance all the way up there