I am a bit confused here, The higher the disc loading, the more pitch on the blades, right? so more air being pushed downwards, but same RRPM, would that air be faster or just more of it?
Disc loading is a function of how big the disc is compared to how much weight it is supporting.
Two helicopters with the same size rotor disc but with different AUM will have different disc loadings - the higher the AUM, the higher the disc loading for the same size rotor. Would that mean higher pitch angles? Probably but only if RRPM and the size/shape/number of blades is constant. There is a ratio called rotor solidity ratio which is the swept area of the disc divided by how much of that area is occupied by the blades.
As engines have become more powerful over the years, it has allowed designers to reduce the size of the rotor disc because more power means you can make the disc 'work' harder.
You are just pushing the same amount (volume) of air downwards (for the same aircraft mass) but with a smaller rotor (smaller cross-sectional area) so the downwash speed has to be increased by accelerating the air more.
I'm no physics guru but I think you are doing the same amount of work (same volume of air) in less time and power is a function of work/time - hence the need for more powerful engines to allow a smaller rotor disc.