Your delivery is the reason for this getting so many downvotes.
However, it is an issue that has merit, so I'll take the bait. This is just my opinion, but there is quite an issue with victim mentality, as well as simple inability to take criticism. When I say that though, I also have to say, in order to differentiate this claim from yours, that there's a very specific set of "rules" to classifying someone as a self-made victim. Firstly, your criticism needs to be and must be constructive and assertive in order to make that assumption.
- "Nunu, you need to ult sooner." Constructive, direct, clearly outlines what you believe is their best course of action. Not aggressive or hostile, but still declares the message you wish to convey - ult sooner, and we have a better chance to win.
- "Nunu, wtf?! use your fucking ult! spam ping ult CD is up" Hostile, aggressive, overall negative. Still direct, still outlines what you think is best...but in such a way that you clearly are clearly displaying contempt of your teammate.
Second, if they become hostile after this, you need to hold your constructive yet assertive stance, and not fight flame with flame. In fact, you don't want to fight at all. Say your piece, and be done with it. If they get hostile, honestly, just keep playing the game and don't bother with them. If you need to repeat that same piece of criticism over and over again after like every other fight, whatever, but the moment you deviate to matching "fuck off noob, reported" with snarky, passive-aggressive comebacks based around what you said and what you see as lack of skill, you're playing chat wars, not LoL.
Lastly, you need to accept that you could be wrong. In my previous example...if I tell Nunu to ult sooner, and he starts trying to ult sooner, only to get immediately cc'd and pubstomped, I cannot keep putting that blame on Nunu. I mean, I literally just told him to ult sooner in fights, and he even tried to oblige. This does not make it a "welp, gg, fucking Nunu" game. If anything, if I were to actually believe that's the case, I would be the one playing victim, in saying "oh, I lost the game cause teammates!" when in reality, my teammates were trying their best and even listening to me. It's possible that the reason for a loss is as simple as "we got fucking rekt." It doesn't have to be "this guy didn't play correctly." As many people who play victim as there are, there's just as many who must make a culprit to feel better, which is just as bad.
If they are playing the victim, it royally sucks. And it's still a much higher statistic than it should be. But it's actually much lower than you think it is. The issue is that there's not a straightforward way to combat it. At least, not individually. So even though it's definitely something that can be established, there's not really a good answer to "what the hell can we do about it?" at this time.