Aside from that, in today's online world, any time friction is added, people come along and make some grease for it. Making a storefront from scratch? Difficult! Using WooCommerce on Wordpress? So easy a sufficiently motivated 12 year old can figure it out.

If you add some system for site verification, first someone will make tooling to facilitate it and soon after someone will offer a service to provide it for you and in a matter of months these spam sites will be up and running just like they are now, only it will be more difficult for a legitimate newcomer to get started in the same arena.