Facebook acquired Parse back in 2013. It's an enormous company and Parse was just a very tiny part. If it's this easy for Facebook to change direction slightly and drop an official, paid-for, supported product like Parse, imagine how easy it is to drop an unofficial, unsupported, free open source project like React.
Contrast this with Aurelia which is essential for the overall success of Durandal Inc.
You might find the discussion here interesting: github.com/aurelia/framework/issues/74
Variety of developer perspectives
Full disclosure: I'm on the core team, so obviously biased. I do not work for durandal inc nor do I receive any $$$ from durandal inc