Authoritative sources are considered reliable > newcomers undermine old sources > newcomers become authoritative sources, repeat ad infinitum.
When small shops sold most products, you could rely on the owner being connected enough to the community to not rip anyone off. As communities and local social connections broke down, the penalty for being dishonest evaporated. Amazon and other competitors took advantage and became trustworthy. Now they are slipping...
My guess: in both journalism and in e-commerce, the next step will be a return to “personable” sources of information that are perceived as reliable. Substack is on the right track here WRT journalism. Something that has real people (with good reputations) review products might be the e-commerce equivalent.