The assumption behind this discussion is that CG intends it to be fair. No, CG wants us to have to develop both the depth and breadth of our rosters.
When they created TB, they pushed us to focus on the breadth of our rosters. It is fully intentional that they didn't tell us that, later, TW would put broadly developed rosters at a disadvantage.
They don't care that GP is a poor metric. They want to push people to gear up toons to be competitive. Fair matchups mean people don't have to change anything.
It would be easy for them to come up with algorithms for closer matches, although it will never be perfect. But what's the incentive?
Maybe CG will listen if we continue to show the unfairness of it, but ultimately they will look at whether people are spending to compete this way.