This is true, but I think it glosses over a bunch of important structure in society that isn't obviously connected to the voter. An analogy might be to say that ultimately, all of your behaviors come down to the neuron. While technically true, it ignores brain structures, hormones, emotional state, etc that are almost always more important in actual treatment than any attempt to deal with individual neurons.

Society is an enormously complex thing with all kinds of hidden influences and imbalances, and I think that saying "it's all the voter" tends to shut down thinking about the real alternatives for fixing problems. I'm not saying that I know what those alternatives are, just that they are likely to exist because we live in a society with structure. Since they're likely to exist, I think we should be looking for them and trying to address them in order to treat this kind of problem.