I think the OP is expressing a very common sentiment. There a lot of people out there with dead weight in their roster and struggling in Grand Arena against more efficient players. Until Grand Arena arrived, it didn't matter that much how you farmed or geared your 10th - 20th characters, and now suddenly (in relative terms) it is critical whether you took Farmboy Luke all the way to Gear 12 to unlock CLS, or did it with just the bare minimum.
Older accounts that chose to level characters that seemed cool instead of saving every credit to stay on meta and be ready for the next meta also suffer with dead weight characters inflating their GP. GA is harder on players who weren't that serious for there first few months of play, or chose to experiment with off-meta characters in pre-GA.
It's a flaw in a matching system based on GP. I don't know if there is a better system, but blaming it purely on 'choices' obscures the fact that most of these choices were made before GA was a thing.