[hueyp]

Swapping out inner html has issues such as losing form data and bound events (etc...). Ignoring that you also have life cycle issues. For instance if you have a component that needs to know its render height you want a hook for calculating that height AFTER the entire DOM has updated. Otherwise you are going to force multiple layouts (bad). React provides these life cycle methods.

As far as the render method being big, the premise React is built on is that the virtual DOM is much faster than the real DOM. Test as necessary for your own comfort / use cases. I personally trust the testimonials of people smarter than me that aren't the React team also feel this is true and are making real changes to their products based on that. I also trust my own experiences that the DOM is slow :)