I agree with your post, good job, except on two points
4. Stupid Theories
5. Supports, and Why They Can Carry (Nope You're Wrong, They Can)
Your whole post seems like a stupid theory, except I don't judge it stupid. You judge others theories like they could judge yours.... I don't like that XD
Also, about supports. 0-1300 elo bracket, supports ARE often reduced not to carry.Why? Because the support gives tools to his team (wards, CC etc.) but he will not dish insane amounts of damage. What his team does with the tools, however, is not in his control, which is why you rely a lot on your team to win. Also, the support is not the only responsible for the ad carry being fed, the ad carry himself has a lot of work to do, and can still carry even if the support does a bad job (it is harder, of course). But a very good support with a very bad ad carry might not be able to win the lane, and if it happens, the support has almost no power on the events. I do often win games with Leona, and sometimes I like supporting, but the reasons above are why I prefer not to.
I've had the support argument so many times and proven so many people wrong I can't count. You're wrong. Support can carry. I'm sick of providing the argument but here we go.
Tell you what, grab a 2300 Elo player who mains support, ask them to jump on a low account and duo with you, have them support, and don't be the adc. No matter who that adc is (90% of the time or more, at least) he will end up fed, because that 2300 support will do such a great job at zoning and setting up kills that the carry would have to be straight stupid not to take advantage of it.
This is the support carrying. He will also ward the enemy jungle @ blue/red (depending on what side he is), and ping and go in with the jungler/mid/carry to counter jungle him and pick up a kill. He'll ping dragon, he'll keep timers, he'll roam to mid and help mid pick up a kill. He'll keep track of jungle locations and ping the jungler when he appears (because he'll have godlike map awareness). At the Q screen he'll pick a viable and powerful support that can do more than lane. For instance if he picks Alistar your carry will never die. If he picks Blitzcrank their carry will die first every teamfight. If he picks Sona their team will be stunned at the perfect time to pick up a kill on the priority targets and take over Baron.
None of this **** will show in his score, but you will have no doubt who actually carried that game. You'll Q with him again, it'll happen again. You'll Q with him 20 times, and you'll go 19 out of 20 games won.
Support can carry. Stop trying to argue that he can't. You're lazy. You don't want the "boring" role. You want to feel justified in your complete ineptitude at the role, because that's what it is - you don't know how to do it properly, nobody does at low elo - that's why all the good supports are gone - they're in the lowest supply and highest demand in low elo, once you get someone who can do it well 9 times out of 10 they'll win 8 times out of 10. The rest are left thinking that support is worthless because...and this is important...they are worthless as a support, and have only seen worthless supports.
I have played with godlike supports, and I've seen them turn games around. I've seen them carry by getting the carry fed, and then continuing on to lead the team to victory. Once your team sees you in the enemy's jungle throwing down wards and calling timers and pointing out the jungler, your team will be like "this guy knows his ****, wow." and they'll start listening to you, following you, and be led to victory.
Any role can carry.