Hydraulic rim brakes came before disk brakes. The reasons they were not as popular is the weight was undesirable to the racing crowd and people didn't like the idea of bleeding them. I have them on my Tandem and they are superior to hydraulic disk brakes in many ways. The drop bar lever versions are no longer made. If I had not needed frame couplers on my current bicycle I would use the Magura HS33s. Disk brakes are more costly and complicated. cyccommute is correct about the rim being a larger disk. The effect of rain on rim brakes is mostly diminished when using hydraulic rim brakes.