Because I have no return values to hold on to. Everything in the render function is a side effect. There's no way to collect the intermediate dom representation in data structures and combine it together later. There is no room for asynchronicity from what I have seen. What if I'd like to combine some reactive streams to send me the desired dom structure as state changes over time, piece them together and send them to the renderer?
True, you don't have asynchronous template rendering, but you can still asynchronously collect data into your own data structures, then keep re-rendering the whole thing with an incremental-dom render function.
