It seems to me like adding mechanics would be difficult work for GMs and it would make grinding for OP status more important than actual RPing.

*I'm gonna officially vote against mechanics.*

However, I still like the idea of a shallow aesthetic of an MMO RPG world.  Where we can RP as 'levelling up' or getting more experience and higher ranked in  guilds.  We don't have to make it strict, I mean we're all gonna have plot armour and uniqueness anyway right. It's more about the writing, for me.