In my experience it's usually the marketing department that want much, not all, of the things that end up setting cookies. It's not that it's a bad idea necessarily, but it's adding tracking upon tracking upon tracking and rarely a request to remove something. Some sales person try to sell marketing "Yet another up-sell tool" or "customer retention solution" and no one considers that the site already have five of those tools installed, 3 of which isn't actually used anymore and the last two we aren't really sure of.

I think it's a scam mostly, trying to convince businesses that they're leaving profit on the floor. The providers of these tools leave real businesses jumping from one tracking/data-mining/customer-spying to another in the hope that it will boost their sales by a few percent. Do we really need to know know that much about our customer? Probably not.