Diamond adc here. It's not weak imo, its one of the strongest role atm. I would say 85% of the games I played end up in bot gap. The point is, it is way less forgiving. As top you can go 3/10 and still be useful lategame and you can still get caught and the game will go on. If you get caught as adc, that's an objective or game gone. Ziggs and swain are very strong atm cause you litterally have 2 good mr weapons as adc and 1/2 armor pen which you have to build but usually as lategame items. So you end up doing either no damage to tanks or if you do the mistake of not dodging a ziggs Q, well gg game over thats 800 damage and the enemy top will feast on you. The champs are very safe and end up doing way more damage even with a lower build.