Google Maps or any other aggregator has an inherent interest in market participant diversity. A lot of suppliers would mean competition, which results in ad spend, which result in higher revenue for the aggregator. Same with Google Search.

It's an interesting equilibrium point. They want local businesses to suffer enough to pay up for ads. But also not too much that they die. A good local business that does not need to advertise because it is simply good is actually a burden to the aggregator even though it is exactly what the end users want to see.

In the past, when I was a in position to build a search engine, we took the trouble of always including organically ranked results that were genuinely good, regardless of whether we got paid or not. I felt it was a long term investment into creating real value for our end users and therefore our service.