But if you want, you can find an 80mm f/1.9 lens for a Mamiya 645.
I've never seen the need for one. Back in the day, if I has a need for one, I would have rented one, because otherwise that extra spped would spend most of its time being wasted, sitting unused.
All fast lenses involve compromises - size, cost, complexity, resolution, distortion, focus throw.
Choosing any lens is a question of weighing the compromises against each other.
If speed is your most important criteria, choose based on that.