^^^ this.
Peoples priorities are different. I play for love tw/ arena first. Raids 2nd. Then tb etc last. My roster is built for that. I don't really "work" on toons til I can reach high gear. Or have a team ready. I also seldom use a zeta unless 7 star g12 with few exceptions ie traya at 5 star. So a tb oriented/collector will get murdered.
Also keep in mind they likely cannot get to complicated in matchmaking. Gp is usually a fair assumption. You will win some lose some. But could you imagine how complicated it would be to try to take into account all aspects of an account for even matching?