The picture shows the distribution in levels on any server. No matter of the type. Can you see what happens at level 60? The process is easily explainable if you think to a stream of water. Till the water can flow its level is more or less homogeneous. But if you build a dam the water will start to gather in that point. The level of the water will rise. A lake will start to form.

This happens to all the treadmill mechanics. Because they are effectively streams of water, they are movement in one direction only. Especially in a PvP envoronment it’s INDISPENSABLE to reach the gathering point because the progression translates in power and the power translates into the possibility to compete. And so to have fun.

So, reaching the last level becomes a requirement. It’s a threshold of accessibility you are required to pass.

This is the reason why Blizzard wants to limit the “slots” available for each rank. Because that system will offer an hard cap that will preserve the “special” flavor of those rewards without transforming them in a requirement for everyone.

My idea also retains this quality because, while you can unblock all the ranks, the system still requires you to have the other roles covered. So only a small percent of the players will be “enabled” to actively use their rank powers.

This is a core issue in a PvP environment.

Planetside also addressed this problem because the “roles” you can unblock are never (supposedly) just direct upgrades. And even the lower ranks are (supposedly) useful in a battle. But WoW doesn’t have a built-in support for roles and a similar system would be rather weak if not specifically developed from zero.