The reason for artist protection is that artists each have a style and sound, and having too many very similar songs close together is perceived as "repetition" and I have seen that over and over in one-on-one perceptual research.I don't think most listeners care about artist seperation with parts of other artist songs. 99.9% don't care. The .01 are proberly working or have worked in radio, or extreme listeners. Radio people falsely think listeners care about such things. They don't.
In fact, is a particular artist is not a listener´s favorite, playing them too close is often perceived as "repeat the same song way to often".