Finer control?. Synced behavior is easier to understand and organize logically. You have the option to write it like a book and execute things "concurrently" (considering its really single threaded in JS).
Single threaded concurrency is not the same as synchronous/sequential execition. You and TC39 folks are telling us that mixing sync and async behavior in the same cognitive space is good? Amazing. Async handling should be in its own cognitive space.