Let's change crit items from adcs!
Oh wait, they already done that...
Maybe something went wrong for them to have been forced to revert them.
I used to like to play adc...
It was my favorite role, I had a friend who played support and it was great fun when we played together.
We did not win many times, we did not win easily... we needed a team to win, it was 5 vs 5 every time (or most of the times)
But then riot guted crit adc's and the great fun we had turned to shit.
I could not do NOTHING i used to do with my champions. I strugled and tryed to adapt.
But crit adc's were dead and nothing worked.
Then the abuse began. Anyone could go to the bot lane and turn off the crit adc to always turn them into NPC's.
The community was happy. they called it "bot diversity". I caled it "bot stupidity". Everyone was happy.
Then i stopped playing adc. My friend stopped to play the game.
Soon the game was not fun anymore, i could do well with other champions but i did not enjoyed the game anymore.
And i started to play less and less. And now i nearly dont play anymore... All my friends stopped playing. It's not fun.
This is how riot games destroy his community one patch at a time. Simply because they don't understand how their own game works.
Answering your question, If your adc goes 0/11 and feeds the enemy adc. You should feel it.
The same way anyone can feel a 11/0

... ANY CARRY
That is called to have a lead, and a lead don't auto-win games. It only makes games more easy to win.
You have to play in a way that you and your team can shut down that lead. If u cant u and your team will and should Lose.
And this applies to any carry champion.
About the "one player shouldnt destroy one team" a agree with you. But this is a team game. The best team of 5 players win.
If it bothers you that adcs are strong late game, that make things unfun because they just auto atack. Remember
... the late game of adc's is a joke compared to this boys.
And if you are not convinced and you think late game adcs are unhealthy to the game just remember one word... BURST.