The point isn't to make people feel guilty. Just do the rest and it will probably be fine.
Honestly, I worry that in the US there was a reaction against the "breast is best" movement because of the worry that people were being made to feel guilty if they couldn't produce milk. I understand the sentiment, but there should be a way to communicate facts while still recognizing that not everyone can do it.
Your wife lost the genetic lottery. That doesn't mean you did anything wrong, or could've done anything better. When faced with the choice between "a higher chance of allergies" and "starving your son to death", you did the right thing if your son survived.
I think society as a whole would benefit from (government supported, modern takes on) wet nursing facilities so that every parent has access to natural breast milk, but the unfortunate fact is that today many parents simply don't.
Advice like this is aimed more at mothers who do have milk production but are considering formula because of the incredible drain breastfeeding puts on the body. Formula may still be the better option (what good is breastfeeding when the mother suffers so bad that it impacts the parents' ability to take care of their child?), but for those lucky enough not to suffer too much from breastfeeding, knowing the health benefits may change their minds, or decrease or delay the use of formula for just a little longer.
As for what will happen to your son: who knows, it's all probabilities. You can't connect a specific allergy to a decision. Some breastfed kids get allergies, some formula kids grow up without any. All these statistics state is that probabilities are a bit more favourable across millions of babies when more of them are breastfed. He'll probably be fine, and if he won't be, it's not your fault or anyone else's.
Now what will happen to my son?