Ball pythons aren't aggressive species. So handling or not handling will not make them more aggressive. 99% of the snakes that are aggressive is due ot hunger or poor husbandry. NOT due to handling being non-existent. I barely ever hold my BP collection and yet i never get bit from them.
And i never tell people to handle there snake to make them less aggressive nor has any other experience keeper said so as well.
And yes most hatchlings you buy arent handled often if at all. Their only fed well then shipped out.