Agree with the OP.
People who track regularly use 18" R-compound rubber.....R tires produce higher decel Gs than street rubber which is really what stresses the OEM system, mainly the pads. The more grip you have the more brakes you need.
19", 20" wheels means few to no R compound tires = less need for more brakes and a larger heat sink, all backwards if you ask me.
When I see 20" wheels with giant 380mm rotors and 8 piston calipers with 300 tread wear rating 30-series Generals I think "doofus".