As the levels of the players keep rising and improving, more and more equipment with higher Tiers will appear. The difference between the normal players and the top Tier players was getting wider and wider as time passed by. However, top Tier players were only one small cluster of the entire population in the game. Furthermore, they were so busy grinding their levels and killing bosses to farm for better equipment. Even if there is a PvP battle, it would only happen between players who are about the same level and Tier. Therefore, the normal players would not really be affected much.
It would be just like normal people watching two rich people fighting against each other. No matter how much money those two rich people had, it would not affect the plebians.