Very true! This is an excellent point. (Furthermore, healing is a more stressful role than DPSing, and healers are more prone to burnout—and raid healing takes more skill[1] than DPSing, so for these reasons they are certainly less replaceable; despite a raid needing much fewer healers than DPS, the supply of good healers is lower still.)
[1] Or, to be more precise: the combination of type of skill set + level of competence + disposition, that is required to play a good raid healer, is more rare than the corresponding things that are required to play a good DPSer.
Very true! This is an excellent point. (Furthermore, healing is a more stressful role than DPSing, and healers are more prone to burnout—and raid healing takes more skill[1] than DPSing, so for these reasons they are certainly less replaceable; despite a raid needing much fewer healers than DPS, the supply of good healers is lower still.)
[1] Or, to be more precise: the combination of type of skill set + level of competence + disposition, that is required to play a good raid healer, is more rare than the corresponding things that are required to play a good DPSer.