The artist tag is used not only for the main performer, but also for other performers involved in making the track. If you tag with Musicbrainz, it adds performers, the producer, the mixer, the engineer, etc depending on what level of data it has for a particular release. They are all artists who perform on the track.
For example, when I click on "Eric Clapton" in artist, I see Blind Faith and Derek and the Dominoes and The Beatles While My Guitar Gently Weeps (etc) there because he was an artist on all of those. I want it this way. This way, if I want to listen to some Eric Clapton, I get all the tracks he appears on and not only solo work.
Sounds like you want Artist to behave like Album Artist. Album artist should be the main artist who is credited on the release. (Blind Faith or Derek and the Dominoes in the example above).