I think that you're not understanding the point what so ever.
What are you imagining that you're going to accomplish by blaming the others on the team? Is it selfsatisfaction? Then it's purely detrimental to the team and your own improvement possibilities.
Do you believe that if you can blame someone else for a loss that there was nothing that you could have learned from that game?
Maybe the 2 tower dives that you fucked up could also be a lesson, or the fact that you didn't watch the mini map enough to TP bot. You never roamed as mid. You went ham crazy hungry as the ADC and overstayed constantly trying to get a tower.
It's not about "if you focus on yourself, you'll carry 1,000,000% of the time", and more about what is effective use of your own energies and focus for your own climbing. If you never look at your own play because you're too busy blaming 'the shit team', you're never going to see how you can improve, and you're going no where.
If you think that people who say 'focus on your own gameplay' are wrong and use someone who is low elo like Platinum (compared to some people who say it) as an example, then imaqtpie who has like 4 accounts in Challenger is dead wrong as well.