[nikau]

>It's super easy to lock up a wheel with rim brakes.

Yes, that's one of the benefits of disc brakes, the "better modulation" you hear about equates to finer control and not locking up the brakes.

[davidw]

Maybe, but I don't buy a bit better modulation cutting braking distance in half.

[seec]

There is no real difference with a skilled operator but proponents of "the better gear" will tell you otherwise, forgetting that their main problem is in fact their lack of skill.

In the end disc brakes bikes are everywhere for the same reason 2 tons SUV are everywhere. It does not have much to do with real needs or actual real-world performance with skilled operators, sadly...