Two different concepts.
You’re talking about work slowing because of increased overhead from more people needing to communicate and make decisions.
The OP is talking about the"bus factor". How many people can leave the project unexpectedly and still have the project survive. E.g. if only one person has access to merge changes, the bus factor is 1 regardless of how many people actively contribute.
The only one I think is reasonable is GraphQL. But that isn’t rest, and HTTP is just one of the transport layers it supports.
For anything claiming to be RESTful, it’s a crime.