I wonder if it wouldn’t put them in a problematic position as a marketplace operator, especially as they’re already abusing their position with their “Amazon basics” lineup.
“We listened to customer demand” wouldn’t as a defense for filtering for goods that go through their warehouse (which also doesn’t guarantee you get what you expected)
And Amazon not letting you filter out third-party sellers is effectively a dark pattern.
bestbuy.ca has search results primarily comprised of third-party sellers, but has a prominent “Best Buy Only” filter at the top of the results.