It's normal that bad players face more persecution than good players, no matter the role. It's just how the human mind works. People only look for culprits when things start going wrong: mobs are running wild, the tank is dying, targets aren't dying fast enough and so on. This isn't a healer specific problem: if you're a crappy DPS or a tank, you can sure that people are gonna call you out more often than not.

The solutions are to practice so you're part of the good players and don't get harrassed, or avoid environments where you do by partying with friends and other tolerant players. You can only expect the worst from random strangers.