so far we've been relying on it and it's been pretty helpful. The developer workflow is right now pretty artisanal and relies on "yep, is green in playground" rather than seeing tests run in our CI pipeline.
the fixtures are essentially a flat list, and our schema is growing quickly. The editor does not allow to provide any structure to separate by business domain. The same happen with the assertions.
I'd be OK running the playground assertions in our CI (not sure if there is API to do that right now) but that still does not address the fact the fixtures and assertions are a large wall of text without structure