Peanuts are one of the specific allergens for what was actually said upthread (early exposure is the best way of reducing the likelihood of developing an allergy) has been shown to be true; the explosion in peanut allergies in the US is a direct result of bad recommendation to generally avoid early exposure which has now been lifted and replaced with different guidance.

That doesn't mean, however, that there is no risk of developing an allergy even with early exposure.

I didn't downvote, but "expose them early and it's not a problem" isn't the advice, the advice is that early exposure reduces the chances of allergies.

In any case, it is a statistical assertion, not a guarantee.

Do you think peanut butter might be the problem? As in most Americans don't eat raw peanuts but processed versions which might be more concentrated and exacerbate the allergies?

The evidence is pretty convincing. You saying "it's just unclear" is just you misinterpreting "decreases the likelihood" to include "to zero".