Just because a business model currently relies on cookies, doesn't mean we should get rid of the privacy law. Maybe the business model should change. After all, if the business model required employees to work more than 13 hr shift (Working Time Directive), then tough, your business model needs changing.
However, none of the big advertising networks is going to let the additional value of tracking customer behavior and targeted advertising slip through their fingers.
That's not the same as "needing" cookies for advertising, though, and it is indeed what the directive was meant to put a stop to (among other things).
I talked over a deal yesterday and like most online campaigns it included a frequency cap (in this case 1/24 for desktop and 2/24 for mobile). You cannot do a frequency cap without cookies. I could have instead tried to sell a static image or whatever you think would work, but that deal would not have gotten done. This was a CPM campaign, so let's forget that as a possibility. How would affiliate advertising work without cookies (hint: it doesn't). So that's out too. Let's try CPC. Perhaps you can do the leg-work for me and find someone willing to pay me per click for anonymous users that may or may not exist, but I have yet to find one.
This is all ignoring the fact that without cookies you have absolutely no idea how much inventory you have and what its profile looks like. Say you get 1M page views a month, but no advertiser in the world cares about that they want to know how many unique visit[ors] you get. A forum with 1M page views could have 10k members and be nearly worthless to advertisers, but a blog with 1M page views could be 500k unique visitors that are very desirable for advertisers. Without cookies you don't know and the result is you won't sell ads. It's very simple.