Because people want to be coddled and told that they are good enough even if they are not. But telling them that they are good enough is not toxic, especially if you don't go out of your way to call them trash, and you give them tips on how to not be bad. Calling anyone who demands basic competency toxic is why we have level 90 players who only cast ice spells and stand in telegraphed AOEs. It is not rude, you just take it as rude, and probably will take anything I say as rude unless it is "you're amazing, are perfect in every way, and do not need to improve whatsoever", so I do not care if I offend you as it is literally impossible to not offend people unless you pretend that they are are perfect and not being carried. The toxic casuals in this game literally think I want people to play at an ultimate level. I just want people to play at a skill level where they can contribute their fair share. This is literally the most basic take of all time. If you disagree with the idea of everyone giving their fair share, you are probably one of the people looking for carries.
I also find not contributing to be more rude than people who ask others to give their fair share. So if not contributing is rude, why is it not punished? Because SE caters to hyper casuals and does not care about the people who are forced to carry them.
And no, learning to tank at an average level does not take years. Keep in mind that I am not expecting people in Duty Finder to be gamer gods. I just want people to use one mitigation on mob packs, or at least do so when I ask them to. But the problem is, that people do not want to improve, and the system in place encourages bad play. I can literally go into Expert right now and do my basic 1-2-3 and I'm technically 'participating'
^ This. You are not a noob past level 60. If you are in Stormblood, you have the experience of ARR and Heavensward. You are not an idiot. If you need more practice, go back to Heavensward dungeons and get the practice. Even if it takes you more time, it is the right thing to do. And I agree with the second point too. The people defending this are literally defending people being lazy and having others do everything for them. Are these people Vauthry's accounts?