Unfortunately nutrition advice is a lot more pseudo-science that science.
Like "low fat": eating less fat should make you less fat - that much seems obvious. But there was never any scientific evidence for it, and now we found that actually low fat products tend to make you fatter. It even makes some kind of sense, if you understand how the metabolism works.
Peanuts are very much the same, I think. Yes, eating peanuts can cause an allergic reaction, but not eating peanuts can cause allergies to develop. Finding the best possible action takes time, large studies and a serious amount of statistics.
Personally I tend to ignore most of the nutrition advice out there. There is some good science out there: for example there are clearly bad substances that should be avoided, and an excess of sugar can cause all kinds of health issues. But a lot of the more sensational statements of the form "x is good for you" or "y is bad for you" are just made up.