Not sure why you say that. Except you're imagining Mozart vs free jazz or something. Both musics have pushed dissonance pretty much all the way.
By "a simple fifth" do you mean e.g. the note G in the key of C major? (depends what harmony exactly) or C and G played together with no harmony, or..
And when you say a simple fifth is "dissonant", do you mean it's dissonant, or "dissonant" (i.e. not dissonant)? So, theoretically dissonant, but not really?
I once lived with someone who listened to no 15 (I think it was) of Messiaen's 20 Glimpses of the Infant Jesus constantly. It's very slow, nothing but super-weird chords. After a few minutes there's a major triad, which sounds sooo weird, like a super-weird chord. So.. that makes "the perception of dissonance isn't musical, it's cultural" not sound exactly right either.
It demands resolution? In what way? Like what? You need to hear a root note after it?
>It doesn't sound wrong to hear tritones
Like in a G7 chord?
>or stacked fourths
The jazz originators of this called it a Ravel voicing.