I conceed that there are some small benefits to the immune system probably through the gut flora during breastfeeding, but it's far from being dangerous to not breastfeed. You are not going to harm your baby by not breastfeeding. A slightly increased risk of eczema or asthma is pretty far from what I've heard mothers worry about when it comes to formula. None of the health issues seen will persist past 2 years by any measure, and the breastfeeding immune system benefit is more of a slight "boost" than a necessity. You are putting your baby in much greater danger by doing normal things like putting them in a car, not to say parents need to avoid ever driving their child, but to understand the relative risks we are discussing. 

I hope not to misinform but to elaborate on why we believe the things we believe and how much of a magnitude should parents place on these "best practice" ideas from the past. All studies have shown no difference after 6 or so years post breastfeeding and the benefits that occur at 6months to 1 year in terms of preventing infection are much more important in developing countries than your typical Reddit user from the US. 

Basically, if you are feeling ashamed or pressured into breastfeeding when it is infeasible or very difficult compared to formula, the science says you can use formula and be totally fine. And I think that's important for people to know.