I was surprised as well, I do believe that default GPS should work regardless. However, I tried 3 different spots and could not get a single location after minutes of trying.
I'm not an Android developer, but could it be that applications are just expecting that API? It would make sense for Google to want to route location requests through what's usually their service...
There are two sets of APIs - one provided by Android AOSP where you choose whether you use GPS, network location or other provider and handle it manually.
And then there's a more powerful version provided by Google Services, which automatically fuses all providers and talks to Google servers. Most apps these days opt for the Fused provider, since it's easier to use and automatically handles getting a reliable location in pretty much any environment. It's not available on "Google-free" phones though, since it depends on Google's infrastructure.
I'm not an Android developer, but could it be that applications are just expecting that API? It would make sense for Google to want to route location requests through what's usually their service...