Why Can't We Just Do Async Await as Function Components?

I had a question about all of this. I always thought bundle size was the main theme, but hearing this conversation seems like data fetching is also just a huge part of it. So why can't we or indeed maybe we can, you know, have react function components called asynchronously at the render phase? It sounds like server components is designed to solve a whole bunch of problems. But what I know tells me this is actually possible is just probably not ideal.