Diallyl disulfide, allylpropyl disulfide, and allicin are irritants. Garlic is also an antibiotic. Eating two raw cloves of garlic could irritate you and also cause a lot of your gut bacteria to die off.
I love roasted garlic, but more than a couple cloves of that and I experience digestive issues.
Try challenging your healthy friends to eating two cloves of garlic raw and see if they have any reactions.