Because mosts music tastes stagnate [sic] after your teens
Assumes facts not in evidence.
Also ignores that pop music, by definition, has the broadest reach, by being the lowest common denominator (no criticism here, it's just a fundamental requirement to be accessible by the most people).
Compare pop music to say, Miles Davis' "Kind of Blue" . Far fewer people can appreciate "Kind of Blue" because it's insane complexity. Hell, I have musical training and can only listen to it occasionally, on the daily I much prefer something far more approachable, some form of more-popular music - even stuff we call "classical" (which was the pop music of it's day).