1. The majority of clicks go to flashy, annoying ads. 2. People who click on these ads rarely convert, i.e. sign up for a newsletter or purchase a product. These are probably accidental clicks. 3. The ROI on advertising is often negative. 4. No one cares about any of this because click through rates are still the gold standard. Advertisers aren't savvy enough to know better, and ad agencies don't get paid either way.
It's a terribly inefficient industry, made worse by the fact that attribution is very difficult ("did this costumer buy this product because of an ad?"). This all has led to a fall in ad rates, which is just leading to more annoying ads. It's a vicious cycle that makes clean, honest text ads even less likely.