I encounter people like this daily. I play a mix of tank and healer, as you are probably aware, healers have a better overview of the entire team. It's easier to see who is messing up, who is dead weight.
There is a massive difference between casual and dead weight. No one is expecting every player to be the 1% ultimate god that can clear the game by playing with one foot and a missing eye on a 800x600 resolution while being 500 meters away from the screen. However it is pretty standard to be level 70 and understand YOUR own class that YOU have been playing to get to max level. The fact that people like you genuinely believe that dead weight players who know nothing and refuse to learn is perfectly acceptable is just mind boggling. You say people who don't know basics are rare, no, they really aren't, they are extremely common. I don't hold any player to any insanely high standards, all I expect from you as a level 70 player is to understand your class and the basics of the game.
According to some, that is too much to ask for.
You are not who gets to decide what's "acceptable" either. Why do YOU need to waste my time into the dungeon and be dead weight? Why do YOU get to wipe the raid repeteadly and no one says anything because of fear of ban? Here's a bit of news that you don't seem to be familiar with, I encounter a lot of players that get mad at people who cause wipes, they get frustrated, and they don't say ANYTHING.
Why? Because SE will ban you. If you say anything, you're putting your account at risk because you dared to criticize. The fact that you think you have the right to waste my time and break my enjoyment and believe that your time is worth more than mine shows a massive degree of selfishness and entitlement.
I see a lot of people such as yourself throw around the sentence "you don't have the right to tell others how to play."
Why do YOU have the right to waste MY time? Why do YOU have the right to cause ME frustration because you refuse to learn and constantly wipe the raid which also wastes my time? Why do YOU have the right to waste the time of everyone else in the party because YOU refuse to learn and get better?
How exactly does this seem normal to you? One side has the right to waste the others time and patience but the other side is not allowed to criticize you for doing exactly that. This doesn't make any sense at all, this is the most selfish and entitled thing I've ever heard in any MMO.
I have never ever heard anyone outside FF14 that believes they have the right to waste other peoples time by refusing to learn, and to add to that, if you call them out on it and criticize, they can get you reported and banned. This is a completely backwards system. Instead of bringing the lowest person up and get him to improve, we are bringing everyone else DOWN. Half the people I know are actively refusing to talk with anyone random just out of fear of them getting offended and putting their account at risk.