OT: When I tried Inferno as a drop-in replacement for React few months ago everything kept working fine. Inferno's author was hired by Facebook and some of his work might have been reused. Inferno was insanely fast and for me super compatible though missing some of the API.

I like Dan's answer and it shows that many are not really familiar with React and its trivial concept (like me before I tried). React is good and manageable even after a rewrite because it has a tiny API (compared to other frameworks/libs in this space).