You are right.
However, the arguments referred to can gain some traction even among moderate senators had this bill changed the actual GC distribution from, say, 60% IT/ engineers /finance versus 40% MD/PhD/nursing to 90% IT/ engineers /finance versus 10% MD/PhD/nursing, as the anti-FIFO argument goes.
They argue that by making the process FIFO, you will admit to permanent residency a disproportionately large number of IT people at the cost of MD/PhDs etc (basing on the perecption that most IC folk are IT).
Except, the argument is factually incorrect. Among the population of international MDs+nurses+PhDs, the IC contingent, I can safely bet, exceeds 50%.