For example, jazz receives a relatively small amount of attention, along with say classical, in comparison to rock music on this site. If you go to rateyourmusic.com, jazz gets its due, alongside rock music, but the music critics seem to shun jazz music, according to this website. The exceptions are Kind of Blue, and A Love Supreme obviously, but that is besides the point.
The foundation of this site is rock, and, specifically, lists by rock critics. Jazz shows up on a lot of rock lists, since jazz and rock ultimately derive from the same roots.
Classical music shows up very rarely on rock lists, by comparison, since the European art music tradition almost never overlaps with American pop traditions. About the closest AM gets to classical music (pastiches like "Bohemian Rhapsody" notwithstanding) are weird outliers like Gershwin and Cage.
As you note, RR, someone looking to learn about jazz or classical would do better to look at rateyourmusic, or, better, a site specifically devoted to jazz. I love AM, but I wouldn't use it as an introduction to jazz--that's not really what it's for (and, personally, I think "giving jazz its due" would seriously unbalance this site).
Hmm...one explanation might be that jazz and classical music are hard to judge on the good-bad scale. Rock might be about digging up hidden feelings and if it succeeds the music is "good". Maybe jazz is trying not "to be good" and that classical music is much about feelings on "the surface" even if the latter can evoke deeper feelings as well.
Many of my musical heroes seem to have a good relation with their parents! Or else, being able to be a good rock musician can help you to bring back feelings you once been trying to save or hide or forget...