On the contrary, I think the one who stole the chocolate bar is guilty, not the shop owner who lacked a "no knife policy" and didn't protect its sweats enough. Or more fitting advertised them too much. The shop owner is just innocent in your example and the blame lies solely on the one who stole. Same with the people committing genocide. The meme that Facebook was a part here is just faulty reasoning.

The "stochastic terrorism" crowd comes to mind, who seem to create a new olympic discipline of reaching. They too like to accuse platforms that were used to communicate. That is just distracting from those that are responsible for the crimes at hand. If there hadn't been a Facebook, they would have used Twitter or any other social media platform.

Advertising is manipulative, but Facebook isn't enabling me to commit crimes. These issues need a clear separation. Otherwise any statement would be too dangerous if you generalize your concept of responsibility. That is not a healthy road to go down.