Reminds me when we lost a DPS in a dungeon probably around HW or ARR time and people were waiting for a DPS because 1 dropped, I said "its fine, besides I Green DPS anyway" . They told me don't and just focus on healing. I insisted they carry on pulling, as you will expect dungeon was fine, I Green DPS'd, nobody died and thus at the end I had to say "I told you so".

At the end of the day as long as you fulfill your top priority, keeping people alive, you have plenty of room to DPS and people who tell you to focus only on healing don't understand how healing in XIV works. XIV is very scripted and there's also no constant stream of healing, meaning damage is predictable and not constant, so that creates periods where if you aren't DPSing, you are doing nothing.