Search 'assisted opening knives' and you won't see any ads about such knives EXCEPT for Amazon. You will also see "Shop for Assisted Opening Knives on Google" which, if you follow the link, will show you a nice assortment of about 14k assisted opening knives. This feels like an abuse of monopoly power.
This may be naive but isn't this just an endemic problem for all social networks. Anything I share on a social network can be copied by people allowed to view it and dispersed. Doesn't it just fall on trusting those you share with? If not, what is the difference?