Is Recommended Songs blackballing Led Zeppelin (and others)?

[nortonmw]

This is more of a compaint or question than an idea, but this seems to be the only way to give feedback. What is up with the "Recommended Songs" feature? Why won't it recommend Led Zeppelin? I have a list of only their music, and not a single recommended song is from them. I have another classic rock playlist with some of their music on it, and again, no other LZ songs ever show up in "Recommended Songs," regardless of how many times you refresh it. What is the deal? What other bands do you all block from the "Recommended Songs."