But that's not where the current "big divide" is with bicycle braking systems. It's all about "Disc" vs "Rim" brakes, whether hydraulic or cable actuated. It just happens that most rim brakes are cable actuated and most higher-end disc brakes are hydraulic. They are all forms of a "mechanical system", so "hydraulic" vs "mechanical" braking is misleading. The 2 main braking systems of interest here are:-

1. Cable actuated rim brakes
2. Hydraulic actuated disc brakes

These ^ are what all the fuss is about.

The other forms are:-

3. Hydraulic actuated rim brakes
4. Cable actuated disc brakes

There is little current interest in the former and the latter is mostly low-end gear, with a few notable exceptions.