Disagree with what? You have a problem in your posting. It's often a bunch of off-point verbal diarrhea. I said the content wasn't a problem, it's the systems surrounding the content that fail it. You just said you disagree but only address the failure of the systems.
Again, totally misses the point. You are trying to address an issue by looking at the result. I am saying that you need to look at the origin. Just look at the reality that the same content can give birth to very different players. You bring up the truth that different people will have different motivations and goals and look at other gaming genres but you don't connect the dots.
Different types of people will play a genre like an FPS, MOBA, or RTS. But, in those games, people generally play to win. They can be bad, play the game incorrectly, be horribly toxic, but at the end of the day, the people who play purely to grief, throw games, and lose are a tiny minority. By nature of fostering a competitive environment, whether it be through a ladder, ranked play, rating, or just game stats, you unify differing motivations and goals into a singular, upward direction -- victory.
It's no different from managing personnel in a company. Everyone is different in what they want to take away from a job and what they want to put into a job. As the boss of a company, your goal is to somehow nullify that variation in motivation and get people on the same productive page. As some very well known entrepreneurs have said, it's sometimes just easier to only hire A players because you eliminate a lot of variance and headache that comes from trying to unify a team of A players, B players, and C players. That's why statics are a thing in this game.
It doesn't matter if you give someone the information needed to do their job or the content to reinforce it if they don't care. What you need to do is make even the most casual player care just as much about the result as a motivated elite player does.
I played a lot of WoW during Vanilla and BC on the largest PvP server at the time. Everyone -- even casuals -- wanted to be geared. The benefits of that gear were massive. Without gear, you were complete cannon fodder to a geared raider. And, because at the time the best gear was all locked behind a massive PvP grind or the hardest raid content, they had to pursue those means for that goal. So, they either had to become a competent PvPer, a competent raider, or deal with getting ganked , camped, and crapped on by people who were those things. When your gaming experience is reduced to grovelling to your guildmates or friends to save you from hours of merciless t-bagging, it's a little hard to not care.
So turning back to FFXIV, what is the goal? For casual players, the extent of their motivation might be to play virtual barbie with cat girls and cat boys. They see a fully geared A8S cleared player and they don't care. That world has nothing to do with them unless there is a cute glamour they want. With that context, how can you reasonably expect them to be motivated to be a better player? Going back to my previous point, the problem is not the content. FFXIV has some of the most challenging raid content in the industry right now. If players wanted to aspire to a PvE standard, it's there.
So, just like I've already said, this grading system doesn't make people care. Why would a bad player care about clearing content a bit slower and with more toxicity? It doesn't get in the way of their ultimate goal. And, it doesn't make good players care about the team because doing so doesn't benefit their ultimate goal. The goal is creating a system and culture where everyone cares about everyone being better at the game because that is aligned with their shared goal.