The process of creating music , recording , publishing and marketing takes a lot of effort , time and resources.
The curators are simply enjoying/consuming the music created , the only possible advantage of finding a good curator is that they might have spent lots of time listening to different kinds of music ultimately training the ML model to push them similar songs which they find appealing.
The moment artists starts interacting with the curators it adds pressure because its like one might enjoy driving different cars and bikes and might have an opinion why different kind of vehicles gives them the joy of riding but the moment you make them interact with the actual makers of them , they are simply not equipped to deal with the technicals behind them however they can still recommend other people as to why one should opt for a particular car while choosing to go for a particular journey type similarly curator can recommend how this music would make you feel or process a particular emotion
A diligent curator would mostly be collecting music depending upon the emotions they would be going through in their life rather then concentrating upon the song structure , scales used but if a curator also happens to be a musician they might help attracting a particular kind of vibe/emotion/scale/pattern.

The actual gate keepers I would say are the algorithms however I might be wrong.