Sure, you don't have to, and not dpsing is recommended if you're not comfortable healing. But, as a healer main, I do find if frustrating for a healer to be there doing nothing.

Had a tam Tara nm run recently with a 54 sch, who linked his coil body armor shortly after starting (who cares, dude). Fairy healed 99% of the dungeon and he literally just jumped circles around the dps the whole time. No healing or dpsing. Wanted to throw him off the cliff.