Healers that don't want to DPS are like DPSes who refuse to move out of AoEs.

[Taika]

Hmm... I notice he also states "So you will still have to focus on healing, and take care of that, but if you still want to help your party members with the DPS, then you may help them".

The usage of "may" is similar to the one utilized in the Hall of the Novice.

Well yes, he couldn't just go there and say "and after that you're absolutely forced to cast your damage spells", now could he?

In any case, what Yoshi P says is not relevant to the argument in any way. How the jobs should be played is defined by the game design: how the abilities and fights actually work.