Basic YAML, sure, but YAML has some insane features that I don't think would be possible to replicate in JSON. Or, at least, you'd lose some information in the conversion.
For example, YAML supports the concept of reusable fragments. You can define a fragment in one place and reference it further down in your YAML file. A JSON converter could take the final YAML output and turn it into JSON but you would lose the context of the fact that in the original YAML it was an included fragment and not just the same section repeated a few times.
Yeah, YAML can also embed arbitrary code in the original Ruby incarnation and that clearly cannot be translated to JSON.
Yeah, no straightforward translation of references to JSON. You could provide both translation ramps, but it would be an implementation-specific convention and not something other JSON tools understood.
For example, YAML supports the concept of reusable fragments. You can define a fragment in one place and reference it further down in your YAML file. A JSON converter could take the final YAML output and turn it into JSON but you would lose the context of the fact that in the original YAML it was an included fragment and not just the same section repeated a few times.