Again, it probably depends on where you live. For me, Yelp produces results that are laughably incomplete, inaccurate and/or outdated. Maybe Yelp is very US-centric or something. Apple seems to go for those partners. They can't give me local weather, they can't give me local movie listings and so on. Google does all of it, even if you live in some puny town in Denmark or Poland. Apple basically stops caring once they've got the capital of each country covered.
Nope, but since Apple is at war with them and have thrown them out of everything except web search in Safari, I don't consider them one of Apple's partners.
They can do whatever they feel like, as long as they make up their minds: Go all-in and be the best, or get out.