TIL the only think that prevents people from farming is the AR and CS.Actually od and hp affect the map greatly. A mapper chooses these stats because they want their map to feel a certain way. These can also be a mapper's trademark *Monstrata with OD8.7 for example. A mapper doesn't need to be able to play their map to understand why it's good, but that topic's for another day.
This is ONLY true for AR10.5-11 because those ARs are usually almost unreadable, but ASIDE OF THAT, your argument just doesn't work. How does changing the OD make the map different ? Or the HP ?
The very VERY rare maps that actually use a very specific AR and CS are maps that don't even give PP in the first place so it would makes them easier yes, but it won't turn said maps into farm maps.
And if people "don't wanna have fun" by putting everything on CS4 AR9, I guess it's their choice, which is still a better choice than the mapper's who most of the time (for kinda hard and hard maps at least) can't even play his own maps.