That's a cynical take, so it will probably get upvoted, but what are you basing it on?
Ebay is a pretty eclectic marketplace and I can think of a number of possible reasons that have little to do with ads. For example, they may be worried about high error rates, and thus buyer and seller dissatisfaction. If I instruct an agent to buy X, eBay is almost never interchangeable with Amazon or Target.
They have no problem surfacing their listings on Google Shopping.
Ebay is a pretty eclectic marketplace and I can think of a number of possible reasons that have little to do with ads. For example, they may be worried about high error rates, and thus buyer and seller dissatisfaction. If I instruct an agent to buy X, eBay is almost never interchangeable with Amazon or Target.
They have no problem surfacing their listings on Google Shopping.