Earlier on, ad relevance was pretty bad and the same ads kept showing. When ad targetting came along, it allowed us to at least show relevant ads. CTR has improved considerably as a result. However, at least for me I'm still getting half the CTR of Google Ads. After some analysis and thinking, I've come to the conclusion that the cause is that Google shows relevant ads per page and there is greater variety within a category.
IOW, if you ad target with Yahoo, some inner pages w/ slightly different wording will have ads relevant to your overall content, but it won't veer too much on pages where it could do so. For example if your site is about clothing, and you did some ad targetting, you could get general clothing ads, both for Y and G. But if you have a popular page on Brand X clothing, Google will keep the category to clothing, but show 4 ads on Brand X clothing. Whereas an ad-targetted domain for Y will still show those 4 more general clothing ads.
I'm wondering if the people who do not ad-target a domain are getting improved ads lately? Is it worth turning off ad targetting at this point?