An alternate way of thinking about this I guess... Have you raided with some regularity with a healer main that was entirely unwilling and unable to flex if even within the shield/pure healer split?

Personally I have to go back to ARR + Gordias and in fairness, the Gordias one was because I was covering a prog team's SCH for a week. The content was too rough to start switching jobs multiple times mid prog when the race was on at the time.