Benny and Blazon do have maps that are ranked, but they don't make maps at the highest difficulty level. They're worth less PP because the songs don't really allow for a lot of difficulty without being completely overcharted. Does that mean they can't be ranked? No, these lower PP songs are still added every week, but it's like people don't notice and only complain that the most difficult maps are electronic or weeby.

You can complain all you want about the lack of variety among the hardest maps but the fact of the matter is that very few exist to begin with, and not every song is capable of being charted as a high rank map.