My best naive wild guess (as a techie, not an MBA) is that a solution is Amazon private brands. Amazon could exercise control over the supply chain, could keep other sellers from piggybacking on a listing, could keep the reviews generally positive (in various ways, including aggressive investigation of suspected fake negative reviews), and could even have customer service treat private brands more favorably than many others. Plus preferential listing and smarter targeting.

Meanwhile, most other brands would still have to be on Amazon, but suffer the current awful environment of counterfeits, reuse of listings for different products, fake reviews on their and competitor's listings, etc.