debuffs

...is what many rdms claim, but when I hit the upper 40s my debuffs stopped sticking. I thought that i was just not able to keep up with the mobs my parties chose to fight (200xp every kill, no chains). But then I hit 51 and got the dark, light, earth(slow), ice(paralyze), and wind (gravity)...

...did these become less important without someone telling me? It's gotten to the point where I'm in a party as a white mage and if I don't cast Frost and Shock, the black mage won't. Are they just not important anymore? Even when I'm playing as black mage (my current support job) I'm asked...