I don't see healers being pushed to the same extremes as DPS roles. As a healer there are groups out there that can and will accommodate a main heal/off heal system to an extent where as no group is going to be like "Wow, this BLM has lower damage but they always mana shift so like lets keep them"... It just isnt true.
I agree there is a lot of pressure on healers to dps but if you can't handle that pressure the pressure on actual dps seems like it won't be for you.