[mstade]

I'd agree with you, and I'm keen to learn the real answer. My guess would be that some initial optimizations can occur without having to also parse and analyze the body of a function, potentially having significant performance benefits to reducing the boot time of a program.

[Klathmon]

the simple version is that because `await` wasn't a keyword before, it can be a named function.

So `await (x)` is ambiguous. Making the outer function `async function () {...}` makes await a keyword inside that function, allowing them to move forward with that syntax in a non-breaking way as the parser now knows that there can't be a function named `await` inside any async functions.