I'm gonna have to agree with that. Keep everyone alive, that's your first priority.

Would it benefit you to learn how to dps + heal? Yeah. May I think to myself "wow that healer sure is lazy just standing there and healing"? Maybe. Will I ever kick a healer out of my group for healing and not dpsing? Absolutely not, that's ridiculous.

Play how you want as long as you're doing your role, at the very least.