Tracking makes markets more efficient.
1. Advertisers can tune their ads/targeting to get higher conversions and sales. They pay higher PPMs and PPCs.
2. Publishers get higher PPMs and PPCs. This motivates them to invest more in their content and website because each new user will yield more money with higher PPMs.
3. Users get more relevant and safer ads. Remember the shady banner ads of the late 90's and 2000's? That's the type of low conversion rate / click through rate ads that will run when advertisers can't target their audience efficiently and PPMs are very low. Relevant ads also save users (the segment that buys stuff from ads) time from researching for products and services.
4. Users get personalized content from publishers. This has a few negatives but I would argue that it greatly improves user experience.
The technical and administrative complexity required for the legislation effectively shuts off tracking for all websites that aren't owned by a megacorp. Small and medium sized publishers now have less motivation to get good content out and improve their websites from the lower PPMs.