I disagree. I had years of healing experience in FFXI and WoW. I healed this game as a natural. If there is ever a wipe, it's someone else's fault, not mine. I've also tanked in both games and it has helped me with certain aspects such as being mindful of your surroundings and enmity levels. Sure, they're different games but the concepts are the same.
I also strongly disagree when someone says "unless you've cleared X in this game..." Those comments need to stop (though they never will).
To the OP, I've only ever had 1 negative experience when I joined a random duty and the tank (with his anima weapon) made a comment about how I had 1 piece of lower level gear (nothing better drops, literally on that job, 90% of drops are Mnk) and made a sad face, saying "fml". The run went very fast and even though he tanked almost exclusively in Deliverance, no deaths at all. People are just judgmental.
