Too much of the same

Why do the same songs appear on different playlists time and again. For eg. Van Morrison’s brown - eyed girl is on multiple playlists across multiple genres.Getting so sick of that song now. Surely he was not a hit till the 70 ‘s .. or have I got that wrong. Where are people like Crosby Stills Nash and Young.? Haven’t heard them once. And their music is stellar. No Eagles either. Much as I enjoy the game I don’t think it is a true record or reflection of the hits of the periods and the genres seem to overlap too much giving the same old songs to different playlists - sloppy editing. Or else cut down the number of subcategories.