Except you haven't debunked anything. You're behind by 6 months because you left a persistent game server. You are more than welcome to create a new account if you want to bypass the time investment of others, but you must also pay the price of forfeiting your time investment. You cannot strip investment advantage from others without either investing your own or simultaneously stripping your own. Yes, that new player can reach higher ranks in arena easier, but they also don't have a roster worth mentioning, they can't do raids, they can't participate in a lot of events (especially legendary). They don't have nearly as much game access as you have, so to say they are better off is a limited view. Again, if you want to avoid the time investment disparity penalty of leaving an on-going game for 4 months, you have to either pay our start a new account. This is the business model the game is based on. They're shouldn't be any changes to it, and they're won't be because it's clearly working just fine for the game.
Top payouts award far more crystals. The fastest way whales get gear is by buying it in shipments, not by farming it or getting it from raids. Switching up shards would reduce the amount of crystals whales get from arena, which would hurt them (just because they buy a lot of other crystals doesn't mean they don't benefit from the crystals in their daily arena payout).