Having implemented a code editor, I can assure you that not re-rendering lines and blocks of code is also a worthy effort. It probably just doesn't fit into react's incremental computation model yet?
Yeah, that's the reason why they tried React I guess. But as far as I can tell they kept the should-update-or-not procedures they implemented specifically FOR React. So what they removed wasn't the concept of React, just the library as their DOM rendering implementation.
