"Can we accept this basic truth?" But can we

Riot backs up this claim: Burst Damage beats Sustained Damage (APC > ADC) Sustained Damage beats Tank (ADC > Tank) Tank beats Burst Damage (Tank > APC)

If this is how they think the game works, they don't actually play the game. If a team has both AD and AP bursters, eg assassins. Tank is irrelevant. You can have vi (hard tank build) and Leona, and we can try our best to lock them down, but they simply bypass us and murder the squishies, what's the point? Why? Why play tanks, hell why play supports. When whoever has the most assassins wins?

This concept of "League of assassins" has to come to an end. If this is a game a teamwork, what's the point of having a champion that can consistently 1v3-5? I have many questions, which I have put here. Much like most questions, I would like an answer. (I don't want to hear that CC beats assassins, if you can burst someone down in less than a second, there is no chance CC off.)