Open ecosystems often have Optional Catalytic Complements.
Open ecosystems are amazing.
They can become ubiquitous, because no one is afraid that by joining they'll become indebted to some powerful actor.
But open ecosystems are also hard to coordinate.
There are some complement roles in ecosystems that are technically optional, but when they work correctly can catalyze significantly more value for the ecosystem overall.
These are things like a package registry, or a payments provider everyone uses, or a search engine.
GitHub is another example.
Git allows an infinite variety of different decentralized workflows.
GitHub provides a single, mostly centralized convention.
You can still do more complex workflows if you want to, but you almost never will.
The benefit of being in the place everyone else is and using the same conventions as them is too valuable.
In these cases, the complement having solved the coordination problem allows the open components to run even hotter.
For these OCCs, everybody benefits if there's an option everybody likes.