You don't need to take offence to me discussing your argument, you know. I'm trying to be civil here, haha. I explained the meta as a means to support the point I was making. Not to insulate that you don't know what the meta is.
As for what you're saying about the short ranged APCs, assassins, etc not being able to carry, well that's wrong. They're able to carry by the nature of their kits alone. They usually just require your team to cater to your weaknesses more. Be that by picking a champion with good peel, or someone who can delete potential threats before they arrive.
I can understand your argument, and I appreciate that you're suggesting being a champion with long range and high damage output means that player is essentially untouchable to a melee bruiser, and that may be true if there weren't items, champions and a plethora of other tools that grant access to those melee characters reaching a long ranged carry in the back line of a teamfight.
Let's say though that even with items like Righteous Glory, or abilities like Vi's ult, you still can't take out the enemies long range carry. That's not because a melee character isn't capable of killing that person. It's most likely because that carry' steam mates are doing their job at peeling the potential threat, which is exactly what they're supposed to do.
You scratch my back, I'll scratch yours. Meaning you protect me from potential threats, and I'll kill the people trying to kill you.
If you had a melee character who was able to just walk through everything and be granted success in the form of a dead carry every time, well that would just be OP.
Tanks make a difference by keeping their carries alive. Not by killing all potential threats. That's the job of assassins.
As far as I can see, Riot are doing their best to tighten the functionality of champions who are built for a specific task, and this patch definitely seems to support that idea.