As with most things in engineering, it depends. There are real logistical costs to using binary formats. This format is almost compact as a binary format while still retaining all the nice qualities of being an ASCII friendly encoding (you can embed it anywhere strings are allowed, including copy-paste workflows)

Think of it as a hybrid between JSON, SQLite, and generic compression. This format really excels for use cases where large read-only build artifacts are queried by worker nodes like an embedded database.