Oh really? I'll reiterate one more time, I leveled Dragoon from 34 to 52 in a single day doing nothing but fates for ten hours. In fact, I don't even think I was done with 2.0 at the time. You know how I figured out Dragoon's rotation? I youtubed a video and adapted the 60 rotation to 50. Not a single quest along the way gave me any hints or suggestions on how to properly utilize my rotation. You don't learn Blood for Blood gives a slight potency increase if used ahead of Internal Release. The Dragoon questline doesn't tell you how to manage Geirskogul or how frequent in your rotation it can be used. It doesn't even mention the skill by name. You're literally just handed it after completing a story that has nothing to do with that particular skill. So what exactly would I be missing had I skipped the storyline entirely, you know, the storyline that doesn't even mention the skills it gives you by name, let alone show you how to use it?
You mean boss mechanics where players currently shout at you if you haven't watched a guide? Since I only joined last year, I did many bits of content out of order. Like clearing Nidhogg EX before more than half the extreme primals before him. I managed to learn his mechanics just fine. Someone skipping ahead isn't going to be clueless. This game isn't exactly difficult to figure out. Not to mention, MrHappy and Mizzteq put out guides within a week or two of new content being launched. Most people are either going into content where everyone is blind to mechanics or they've watched guides.
And bad players will always be bad. They don't care. Inexperienced players generally want to learn how to play properly and will readily accept advice when mistakes are made. I recently had a mentor White Mage who stood still and did nothing while we mowed down mobs. This person was wearing ilvl 250 gear, had it all melded yet he couldn't be bothered to even turn on Cleric Stance once. Evidently, the MSQ and job questline didn't make him give a hoot about DPSing.