Everyone? It doesn't matter what you "believe", because it's....a fact.
Carbohydrates (ie bread and sugar), are converted in your body to the same thing: glucose. It doesn't matter if it comes from sugar or a slice of bread. It's literally the same thing wrapped in a different package.
This in turn raises your blood sugar which is toxic to your body. Then insulin comes out to deal with this excess blood sugar, storing it as fat in your cells, making you fat. So there's a bunch of negative things happening at once.
I don't know why this seems to be nonintuitive for people. Maybe because they've been told growing up that bread (grains) are healthy for some reason and you're now anchored to that belief?
http://www.hsph.harvard.edu/nutritionsource/carbohydrates/carbohydrates-and-blood-sugar/