It might be. My kid is allergic to milk he is almost 2, and because of that he is still breast fed. He is allergic to some other things, but the most important one is milk, because it used in so many produce (Not the milk per say but also the milk by products used in other foods).
Seems like most formula is made from cows milk, and breastfeeding is not always an option. My wife had trouble in that area, so we had to move to formula after the first month. There are some alternatives, but they are very pricey.