Your analogies only work if you don't take in to account there are different degrees of utility/quality/usefulness of the product.
People absolutely crusade against dangerous food, or even just food that has no nutritious benefit.
The parent analogy also only holds up on your happy path.
I was just pointing out that arguing against crusading by using an argument (or analogies) that leaves out half of the salient context could be considered disingenuous.
The difference between:
You're using it incorrectly
vs
Of the ones that are fit for a particular purpose, they can work well if used correctly.
Perhaps i'm just nitpicking.