I’m fairly new to this game as well, and while I too am loving building up a tanking job (as well as healing), I started with a dps job (BLM) and this far I’ve had absolutely no issues with completing any and all quests.

I know what you mean from WoW, tanks could do open world content SUPER easy compared to the other specs, but so far in FFXIV I’ve found it to be pretty even in terms of completion speed for world content. Tanks do have better survivability, but conversely dps specs do so much damage it’s usually not a concern, lol