Cannot promotional companies trade boxers ?

[Cent0089]

Probably best current boxer, Terrence Crawford is under Top rank boxing and they obviously cannot give him career defining fights against top boxers which he deserve. In other sports, players are traded all the time. What about exchange Terrence Crawford with lets say Gervonta Davis, who under PBC is fighting B class oposition too? Amd we can get ultimate fights like Crawford - Spence and Lomachenko - Davis. Of course, Spence and Lomachenko are fighting top oponents now, so maybe i put wrong examples. And sorry for my english :)

Edit: i can imagine Crawford - Spence being huge megafight, something on Canelo - Golovkin level of popularity. Or not ?

[Onetimeonly]

Crawford makes more money than anyone but Spence or PAC.