Being a good driver and a suspension guru go hand in hand.
Being able to game the system and tweak stats (power, weight, overall tire grip) is fundamentally different. The precision you are allowed in changing those stats is irrelevent.
The constant pursuit of a technological edge may exist in real life, but generally the person with the most money wins in that aspect. In sim-racing, that changes to the person with the most time available for testing. Suspension tuning requires enough testing as it is, and you want to throw overall performance testing on top of that?
We have the opportunity to ensure everyone is driving essentially the same car (suspension balance preferences aside), resulting in the utmost in fairness. Why throw that away?