The co-founder of simple modern has posted the thread on twitter provided with the link. He also wrote "Problems - Paying for Organic Purchases: If our ad is #1 and we have the #5 organic placement, many organic customers are now buying through the ad. These sales make the advertising look overly profitable. In reality, they are inflating advertising returns and justifying more spend." 

1) Explain why the advertising returns or the ROI has inflated.

2) Briefly draw the parallels of this remark to the findings of the Ebay paper (what Ebay learned from the searching advertising experiment and why they got the result)

https://papers.ssrn.com/sol3/papers.cfm?abstract id=2444538