Well yes, Virtual dom simulates Real dom and every other framework renders virtual dom every time something changes in state, but in this case Radi don't use virtual nodes and automatically reduce unnecessary writes to Real dom as mentioned in article (by binding state to dom).
I always thought this! No matter how fast the Virtual DOM and diffing is, at it's core you are doing 2 writes. If you could just directly manipulate the DOM, that would always be faster. Really cool that someone put it into practice. I'll try it out when I have some time.