Facebook is in a very interesting position regarding React, React Native... because we have very few "apps" and largely operate (or at least try to) as monorepo. This means that we invest in the infrastructure for wiring up everything (linting, IDE integration, bunding, shipping...) once and everything at Facebook uses the same one. This is a stark contrast from the open source world where each project or sub project is a separate repo and you've got to setup everything from scratch.
We have another stance which is that we try to only open source what we use at scale, to make sure that it's actually good.
Those two things are directly conflicting with each others: we can't really open source and do a good job at the workflow that most people use outside of Facebook.
For React, the plan was to wait until the community figures out a canonical way to integrate it into their stack and them promote it out. Unfortunately it didn't happen and after 3 years we just went ahead and did it ourself with create-react-app.
For React Native, we're in a much better state for an unexpected reason: unlike with React where a lot of people integrated it with their existing codebase and infrastructure, with React Native, a lot of people started using it from scratch. So, the task of designing a streamlined experience was much easier and we've seen really polished things like expo, create-react-native-app and ignite coming out of it.
I'm super excited to see non-Facebook companies not only invested in using React Native but also to provide some core features. This way we can really get each piece of the stack being worked on by the people with the best knowledge.