I don't use as little soap as the article suggests, but I use less than many people do. I don't want to smell bad, and I know it's harder to judge your own smells. But there's one piece of trivia that gave me the confidence to try it.

Humans have two types of sweat glands: eccrine and apocrine. Eccrine sweat glands are found all over the body. Apocrine glands are found in armpits (and a few other areas), and they only activate at puberty. The smell is related to bacterial activity in the "apocrine sweat". Armpits don't smell because they sweat more; they smell because it's a different kind of sweat.

So I use soap for my armpits. If I don't, I'll notice the smell easily in a day or two. But for most of my skin, I can go pretty much indefinitely with just water. I don't notice any bad smells, and I have asked some close friends, and they don't smell anything either.