And then there are sites like Pinterest, that degrade the web's utility for the vast majority of people on Earth. It actually harms Google's search experience (obviously image search) and frustrates us that try to benignly browse images. Why does Google let Pinterest get away with its user-hostile approach?
I find the Resurrect Pages firefox extension very useful for a lot of paywalls.
The use of Wikipedia's information in search results is generally useful to the user.
Pinterest's spamming of search results can harm the user experience, making it harder to find content that is hosted elsewhere. Often the content elsewhere is better than that found on Pinterest because it is more likely to be the original source (or at least cite the original).
I'm not sure that Pinterest's mission is the same.
If you generate money for them, they index you, even if the content is bad, and vice versa.
Answer: Yes
If Pinterest is a buyer of Google's ad services, Google has a strong interest in ensuring that Pinterest doesn't get free organic results. More organic results, less need for ad spend.