If anything I would expect the nonexistence of NIMBYs to be a good sign for the good-faith YIMBYs because it suggests that the opposition to their preferred policies are both more reasonable and less unified than the existence of a coherent NIMBY ideology would suggest. Of course if your YIMBYism is just a subset of technocratic authoritarianism then the fact that NIMBYs aren't an actual thing is both convenient but hard to acknowledge. Crushing a mirage under your boot in the name of Progress and Civilization is easier than crushing actual people, but if that reality becomes too obvious you start looking like Star Wars kid.