Why is riot not adressing the Burst damage that Adc's currently have?

First of all, this is not a salty post. Every game I play, I notice one thing and that is how every damn adc is building , depending on the adc you're playing, and either 1 or 2 AA squishies. It's not even about sustain damage anymore. Yet, as a heavy mage player, I find it ever so hard to get that brand combo when minions are in the way whilst all adc's do is AA. A vayne coming out of invisibility and nearly 1 shot's you and then AA to death has counter, right? I remember when i used to cry about assassins bursting you in 0.5 second but now if an enemy team has a fed adc, there is no way that any player in your team can do anything, especially if the enemy support is decent. Actually, in that scenario it is better to avoid the adc incase you feed it even more and stall the game but alas, the paper towers do not allow that as well.

At least Zed requires skill and is easily countered if you know how his kit works but with AA adc's.... I don't think the issue lies in the adc's or supports but the above items that adc's are abusing. If adc's are given burst then at least allow some form of counter or reduce their sustain or even remove it completely. I know for a fact that currently adc's are bursting faster than mages who not only lack sustain but are also mana dependent. The only place where mages win over is in having more range and AOE.