I wonder if we just would disallow affiliate links in general. I.e. you can still create your own webshop, take orders and forward to someone else (similar to dropshipping) but basically outlaw the process of collecting money/commission just for a single placement of links. Or at least, force those sites to correctly mark themselves as "Advertising".
The people doing actual, good reviews/guides also use affiliate links. Getting rid of affiliate links to get rid of the bad actors gets rid of people trying to do it right. The bad actors will have another path in within a month while the person who was run out of their honest business is left hanging.
I think affiliate links are positive for Amazon, because they crowdsource aggressive sales and marketing, but are negative for Google (and everyone else). I think if Google could somehow ban affiliate links, they would.
A second order policy problem is to design good policy to make good policy makers. Meaning that it's hard for a public company entity to codify company policy so that their people in charge of search results are not at all susceptible themselves to sliding in an advantage here or there to assist some group that they become financially enmeshed with.
