Yes, guns don't kill people without pulling the trigger. That doesn't mean that everyone else is without responsibility. Obviously there would be no guns to shoot if nobody sold them. There would be no guns to sell if nobody made them. And so on.

I didn't mean to put all the blame on the users of the infrastructure. Actually I was thinking about the case where the user is involved in creating the infrastructure in the first place, and then pulls the "It's an algorithm!" excuse.

If the infrastructure is made available for someone else to use, then part of the blame for abuse also lies with the person who decided to let them use it. But even in that case it's not the infrastructure that is the problem, it is the lack of access control and accountability.