It was a general reference. When tracks are layered even small differences can become even more noticeable. For example a quad tracked panoramic will usually exhibit more prominently any deficiencies than a single track, or even a stereo track. 1 db cut or boost in the pair of frequencies we have been discussing will absolutely be distinguishable in most scenarios. If had the time to create a parallel clip demonstrating this I would, but the KPA has already consumed way more time than I initially anticipated. Anyway, try it for yourself if you doubt, just make sure the Q isn't unrealistically narrow. If you try it and cannot hear a difference then your monitoring setup is where the problem lies. That said, we are not talking just frequencies, there's likely more going on in the gain structure itself (or other attributes) which all combined we hear as frequency differences.
The video Michael_dk posted pretty much makes the case for the stacking myth. That said, EQ is a large part of it. I posted this earlier, but after EQ'ing the original clip posted by the OP, the differences are fairly inconsequential. I mean, there's a difference in the gating between palm mutes, but tonally they're fairly identical:
