> company X spends money on ads, then turns those ads off and finds that the revenue does not change. Then the conclusion is made that ads don't work.
Did you even read the article?
They said this in point 1 (!), the one of their first points of their conclusions was that advertisement is adviced for start-up companies.
They explicitly said their conclusion wasn't that ads didn't work. I find it hard to believe you read the article and somehow not read that part.