Whilst this is true to an extent, the demands in that regard on Dunk, JPVH etc at the back, are still way less extreme than those of the CMs. The CM are generally receiving and moving the ball on, in tighter spaces and with far less time. It is very, very different in the middle of the park...
There is absolutely not a chance, that any of Igor, Webster, JPVH, Veltman or Pervis could cope with the close range, first time passing required of a CM in RDZ's team. It would be a disaster.