It's because people have been using these products since childhood and they don't think about it anymore.
I agree with you personally. I don't use any products and my skin smells very good. And first thing people say when I say that is "people don't tell me I smell bad", because they can't imagine that someone can actually smell good without using any products.
Why don't you go and read scientific papers if you are not interested in opinions and claims?
Humans beings like to exchange ideas and experiences with eachother without being forced to show scientific evidence. Maybe you don't, which is fine, but maybe not tell others what to discuss then?
This is not a scientific journal, if you haven't noticed and picked the wrong url...