Keep in mind that RP requires interaction between players. The community behind PS is great, so if you're good at RPing you are going to have fun. And yes, you can always challenge other players to duel or participate in tournies but, again, it's a lot more fun when you have a RP purpose behind it (check the dwarven wars for an example).
Besides, developing your char through powerleveling or item hunts only doesn't make you the "strongest", especially considering that our chars can be wiped any time now. But if your char has a personality, that will survive any wipe and other players will remember who you are. that makes you stronger that all those PLevers out there, which in the same terms become the weakest of all.