a. hinders, separates noobies from higher lvl players who might be able to help/mentor them
b. Not if you have a decent computer
c. Would it be considered phasing if there is a shut door that becomes opened for anyone who has completed a quest for it? but everyone is still on the same map and can see each other, just some dont see that door as opened?
Or same idea only with an npc that shows up in town after you complete a quest to rescue them
Those would be good uses for it
ps. if that isnt phasing what game mechanic term is that?