I'd just like to mention that this is definitely not the case for everyone you meet, and I think the correlation to PL'ing is a little off base. Some people just don't bother to seek out knowledge in any form and those are typically the people who cannot perform their jobs well. People who don't know how to tap the vast resources available to them from just asking the people they're partying with or browsing the lodestone information sections are most likely going to fail. Any time I don't know something, I'll ask those around me and also do some searches through lodestone and various fan-sites.
I knew plenty of people in XI who had a 75 and were complete morons and couldn't function on the job (pre-SMN/Abyssea burning). In fact, most of these people I knew only had one job capped, and couldn't do it well. I think because these FF MMO's are more strategic and difficult than most, some people end up at max level without really knowing how to perform their job well.
Also, just on the flip-side - One of the people I frequently do runs with in XIV was doing Ifrit 3 days after he started playing. He leveled LNC, unlocked DRG, actually researched the fight, and started making groups for it. This is one of the better players I play with. Time invested in the game does not = skill in the game. Skill = skill; someone who has greater knowledge and experience in other similar games is going to do better than someone who's first MMO is this. Even some people are just horrible... I hate to say that but it's true - some of my FFXI LS's had complete idiots that had been playing the game for years and seemed to be drunk whenever they played (though never really were).