I hope this insight is helpful. The leveling system is meant to deal with the large number of players who wish to get better equipment but never could in the past since they could never drop their average scores low enough to change tiers. This led to a lot of quit games and score padding to only record your best scores to move up tiers. Many times this lead to players being in tiers they did not "belong", plus the frustration of people quitting in the middle of rounds.
With the new system the tiers are meant to group people of similar skill and not a mechanism of advancement. Players who focus on their tier and try to climb the tier ladder by not recording their all their scores will have a sub par experience. The leveling system is now the primary mechanism to advance. Everyone can level up and access all the equipment in due time.