Maybe I just don't know what modulation means, but I figure it's when you pump the brakes to prevent skidding. How do disk brakes eliminate the need for it?

HN wouldn't let me reply yesterday so I edited my response into the parent comment.

Bike brakes aren't a binary system. You can adjust your touch on the brake levers to apply varying levels of friction against the braking surface to shave off speed. Hope this helps!