It was basically something like the following: "This is no good - if the search results are too good then people won't stay on our page long enough to see the ads"

This is basically what triggered them to start their own company instead of licensing the tech (I'm remembering most of this from In The Plex which I read a while back).

Basically it's stupid not to make the core thing better - especially in the case where Walmart's real competition is Amazon.