Why PPL say RWD is for racing, and FWD is not for racing?

ok i heard alot of people saying that RWD is the real way to race. And its bad to drive FWD for racing? I dont get it, because ive seen some FWD that run just fine on the tracks beating some RWD as well. SO whats going on? It got to the point where i saw this quote online. "FWD like having with your sister, it may be fun, but it is wrong." weird huh