In theory, yes. but on the other hand, when you use bigger sub for your 5.1 system mids/highs aren't actually getting changed, I was thinking about something like 2-way drivers or simply more advanced ones, so that bass would kick in only when it's being called and it wouldn't bleed into mids making them sound unnatural even on very bass-light songs. I mean, surely, bass can make other freqs a little bit more silent and it's very much a natural thing, but when other tones become distorted/unnatural as well, that's the problem with the drivers and not the chosen sound signature.
Let's say we have 3-way speakers (one driver for mids, other for highs, 3rd - lows), adjusting EQ simply makes one of the drivers louder without changing the tonal response for the other one. When bass is set to sky-high levels and we are playing the song with no bass, it sounds the same as if EQ was off. Unfortunately, with casual HPs it's not the same at all, if we highly EQ bass, it's like mids are starting to get perceived as lows even if there are no bass in the background.