Non-american here: if you get to the point where you want to kill another person or groups of people, it doesn't really matter whether you are left/right/pink/blue/whatever. You are unwell. To blame an entire group for one person's mental break is silly. You have no idea what is in another person's head, what their beliefs are, which of those beliefs are conflicting with each other. You might as well say that because the person ate pizza on the day, that we should blame and ban italian pizza places. Silly.
I live in a very broken country too, but our people are not shooting up random places/people. We have many guns too, so we cannot attribute it to that.
I think the kind of person that is willing to kill others (in the american sense, shootings), typically are highly suicidal but since they are able to blame the society or some aspect of society, they come to the conclusion to not commit suicide but to rather attack the system as a final punishment / giving up moment or to assert that they have some form of control. They ofcoarse find no relief there either.
Meanwhile your media and politician use these people as scape goats and cheerleaders for their own agendas. Disgusting in its own right.
Killing innocents is for the unwell, but assassinations have been a staple of politics for as long as humanity has had politics.
It also doesn't follow that an entire group can't be held for a single person's actions. There are plenty of organizations that go out of their way to shape individuals' ways of thinking in order (or otherwise compel them) to harm groups of innocent others. Those groups can and absolutely should be held accountable.