The Anti-ADC Meta
It feels like whenever a new champ is designed, the goal is for it to be highly durable and have enough damage to be good at killing tanks. When that happens, they get really, really good at killing ADC's, because they're doing lots of damage and are hard to kill.
Take Illaoi, for example. People complain about how she does a whole shit-ton of damage, while other people say she's completely balanced. You can tell that the person complaining about the damage was playing a squishy champ like an ADC, and the one defending her was an Illaoi main some other juggernaut that doesn't instantly die from three of her tentacles.
And with items like Lord Dominik's Regards, it's becoming much less beneficial to actually build lots of tank against ADC's, so they just build even more AD to do an even bigger shit-ton of damage.
TL;DR: I know that ADC's are designed to do lots of damage and be squishy enough to be stopped, but lots of champs lately have been able to do lots of damage, too, and be nearly unstoppable. If you've ever played an ARAM, and your team was a bunch of ADC's and assassins, and you were put up against five full tanks, you'll know exactly what I mean.