Once upon a time, everybody smelled like everybody smells, which is to say, probably not quite as pleasant as people smell now -- arguably. Then somebody came along and invented deodorant, began marketing it to women to give them a competitive dating advantage -- "Smell better than the next woman and get more men" -- which they (historically obviously) fell for, and now deodorant is considered necessary... but for what purpose?
People are very adaptive to smell, and beyond the same statistical outliers we have now, generally speaking, people would have smelled about the same. Now though, the bar has been arbitrarily raised, and the result is that everybody not wearing deodorant is a grotesquely smelling freak, where the only outcome is that, once again, we all smell the same, but slightly different -- and of course, we're now all spending an extra $10 a month on a product that nobody really needs, but that was marketed well enough initially that it's become a staple.