Wow has them but it resets in 2-3 days I think
Where are these timers in WoW? There are none. They have timers for PvP (WG, honor gain, arena point gain) to prevent people from completing it all in one sitting (which is not a limiting factor so much as a preventative one). They have Raid resets every week to prevent people from getting geared up too fast (for the same reasons). There is nothing to prevent a person from spending 36, 48, or 72 hours straight playing WoW.

I can see an implementation of this system being incredibly good, if well done, or incredibly bad, if done incorrectly. The system that Ouch! outlined seems pretty solid to me, despite disliking the idea of limiting a physical ranking/level and instead putting more focus on the job level. It is still a good idea in theory, but it needs some work.