I can do whatever I want, but I can't want whatever I want. If person X couldn't have influenced the good/bad outcome of a situation had they wanted to, then that person is neither worthy of praise nor blame. Blame alters wants in people, but as it doesn't telekinetically control inanimate systems, it's a waste of effort to blame them.

Blame is sometimes a useful thing, sometimes not.

The consequentialist model of blame is very different from the deontological model. Because all actions are biologically determined, none are more or less metaphysically blameworthy than others, and none can mark anyone with the metaphysical status of "bad person" and make them "deserve" bad treatment. Consequentialists don't on a primary level want anyone to be treated badly, full stop; thus is it written: "Saddam Hussein doesn't deserve so much as a stubbed toe." But if consequentialists don't believe in punishment for its own sake, they do believe in punishment for the sake of, well, consequences. Hurting bank robbers may not be a good in and of itself, but it will prevent banks from being robbed in the future. And, one might infer, although alcoholics may not deserve condemnation, societal condemnation of alcoholics makes alcoholism a less attractive option.

So here, at last, is a rule for which diseases we offer sympathy, and which we offer condemnation: if giving condemnation instead of sympathy decreases the incidence of the disease enough to be worth the hurt feelings, condemn; otherwise, sympathize. Though the rule is based on philosophy that the majority of the human race would disavow, it leads to intuitively correct consequences. Yelling at a cancer patient, shouting "How dare you allow your cells to divide in an uncontrolled manner like this; is that the way your mother raised you??!" will probably make the patient feel pretty awful, but it's not going to cure the cancer. Telling a lazy person "Get up and do some work, you worthless bum," very well might cure the laziness. The cancer is a biological condition immune to social influences; the laziness is a biological condition susceptible to social influences, so we try to socially influence the laziness and not the cancer.

The question "Do the obese deserve our sympathy or our condemnation," then, is asking whether condemnation is such a useful treatment for obesity that its utility outweights the disutility of hurting obese people's feelings. This question may have different answers depending on the particular obese person involved, the particular person doing the condemning, and the availability of other methods for treating the obesity...

The causal forces leading to an event could be analyzed and disentangled, and only a fraction of these forces are actions, which could have been different had people willed differently (though they could not have willed differently).

At some of the people whose willed actions were significantly behind the bad event, it makes sense to say "boo!" at a certain volume (i.e. to condemn them) to change the configurations of everyone's brains, to make the culprits and bystanders less likely to act badly in the future.

At some of the people whose willed actions were significantly behind the bad event, it does not make sense to say "boo!" to them, as that would do more harm than good.

Whether an opportunity for condemnation ought to be taken depends on the circumstances around it, including people's beliefs, even the untrue ones.