put it like this if you have hybird people will only want hybrid in there party. "why have a single role when a dual role can fight and heal vs a role that can do only 1 thing". right now the game is balenced with a broken paladin. tank should tank, a DD should kill stuff, and a healer should keep people alive.

already happened in FFXI where RDM was the only mage and nothing but DD's in a party. excluding most of the 15+ other jobs.