The main selling point of React is that it is actually tested against millions of users and browser configurations as a part of Facebook UI.
Of course React is much more tested and probably more solid at this point and Riot 2.0 is just released.
But one major benefit for Riot is that there is indeed 24x less code to maintain and so much less weak spots to take care of.
Not that you said so, but it's something one can think when he hears that Riot might be "missing stuff".
The main selling point of React is that it is actually tested against millions of users and browser configurations as a part of Facebook UI.