I think the relative "power" of a music genre is in relationship to its popularity compared to the popularity of what you usually listen to. Stands to reason that if you listen to rarer music (i.e. stuff the algorithm has less information about), then stuff that is more common (and the algorithm knows more about) will have a disproportionate effect on your recommendations.

This seems to be a problem with this general type of recommendation algorithms in general. YouTube suffers from it as well.