To be fair, playing a healer and maining a healer are two very different experiences. Maining one and occasionally playing the rest is a very reasonable expectation.

...that said, who are the healer mains, and what are they doing? Actually, since the healer experience breaks down at high skill and knowledge levels, is there a person who tests extremes+ on exclusively healer? If there isn't, perhaps there should be one, since players tend to latch on certain jobs and that's how mains are made. The experience of that tester might be a good enough simulation of a healer main under repetitive farming conditions.