Honestly, my impression of this site is that the creators don't listen to much music. I know it’s probably not true, and that it sounds pretty snobby, but for instance, segmenting by a genre as broad as Rock is too reductive. There are possibly hundreds of rock subgenres, many of which have very different audiences, with some overlap. Take Pop Rock vs punk vs grindcore vs metal vs folk rock vs whatever. And then all of the subgenres within those. Subgenreception.

IMO, community curation isn't something that will work very well with music, though I'd love to be proved wrong. Somebody said something about subreddits in another comment, and that analogy seems good. There is also another startup that collaborated with metal musicians and had them build out radio shows, which also seems promising - especially because it's addressing a very specific market.

Also, 20 seconds is way too long to listen to a song that you know you're not going to like from the first couple of seconds.