Their discoverability was awful.

What about how AliExpress' search works? The first few listings will be prior viewed items, typically wildly unrelated to the current search-- just remarketing ads based on products visited. Then the things labeled as ads are even more outlandish and inappropriate (serums, pills, pseudo-scams)-- but I guess the ROI is there, else they wouldn't be running them. Similar to the old days of FB where any scammy rebill products were allowed, then once an advertiser base was built, they canned all of the exceptionally unscrupulous advertisers.