[gmueckl]

You know that GPUs can dispatch work dynamically themselves to overcome this problem, right? So you totally can have one computation step determine how many instances it requires for the next one.

[pcwalton]

Yes, it's possible, but why bother when the hardware can rasterize triangles in silicon? :)

[gmueckl]

Because it can't handle them in the prculiar fashion that was described? And it is worse for quads.