If you took the time to think about what I wrote you'd see that I'm not talking about getting people to understand why they're kicked. I'm pointing out the obvious - that if people put forth a little effort to learn how to play they mostly will not GET kicked. Of course, you ignored ME that time but for you it's OK, right?
An easy, though imperfect solution to informing someone why they were kicked... Have each person who votes Yes be required to choose from a drop-down of common reasons. "Seemed AFK", "Low DPS", "healer could not keep us alive" etc. Perfect? No, but if someone is told, especially repeatedly, that they're doing the same thing wrong they might correct it.
Normie - you seem to be an RPer so RP this scenario. A group of adventurers is going to confront danger. As they venture deeper into the dungeon, they notice that one person seems oblivious, as if they're not really there or perhaps incredibly incompetent at their role. What would that group do? Wouldn't they likely remove the person and find someone else to adventure with?
Also... who made you arbiter of the right and wrong way to play WoW? I don't RP, have no interest in it. I don't insist RPers stop RPing. You continually excuse poor play no matter what. I get the feeling someone could do 1k DPS and you'd defend that which makes you ignorable. The fact is that in game or in RP terms when someone joins a group they're implicitly saying that they can and will perform their role competently. Not amazingly, but competently. If they cannot or will not do that then the group is well within its rights to remove them. Of course you'll tell me this is mean or some such... and ignore that you're putting the welfare of one person above that of the other four people.
PS: even if you want to RP and ignore things outside of the game world that doesn't excuse a player for not asking INSIDE the game. Ask in guild chat about the basics of what you need. But if someone refuses to ask in game, is too precious about the RP aspect to use outside sources and cannot or will not learn by doing too bad.