To give some perspective in FCoB, you don't need healer dps to meet enrage timers unless you're in cutting edge progression/world first. The latter puts yourself in a scenario where the dps is doing the bare minimum, if not less than the required dps to meet the enrage timers. They typically have more than enough hp to survive damage nukes like megaflares because they're using melded accessories to meet the hp requirements (which in return lowers their dps).
Cleric Stance is what separates the good players from the mediocre players. Though at the same time, I do not put my expectations on a pug healer to have to mix in their dps (especially if they're not comfortable with it). It's what you see in dps and tanks as well; whether or not they go above and beyond their role, whether it be surviving big pulls or letting a 10-20 minute expertise dungeon come to pass.