[Pitch] Inherit isolation by default for async functions

I'm genuinely surpised to hear these suggestions, because my experiences have been exactly the opposite. I haven't yet encountered a situation where I've wanted some kind of stateless background type. But I have regularly found places where I have this one tiny bit of synchronous work that can be expensive and can and should be done off-actor. JSONDecoder is a fantastic, real-world example. This is the critical concept. I was just imagining what would happen if we made this change without t...