Along with React, GraphQL and a bunch of other technologies with various degrees of popularity https://opensource.fb.com
Along with various startups building around the projects incubated at Facebook - Asana, Interana, Phacility, Qubole, etc.
You don't think those technologies could have been developed by people at ethical companies, or even by the same people at ethical companies?
There's also financial support for building a community around improving the tech, by encouraging outside contributions via meetups, conferences, social events, better technical documentation, etc.
At smaller scale startup an engineer is surely welcome to work on his skunkworks project, but justifying expensive large-scale architectural undertakings on company's dime is problematic. Especially if a quicker fix is available and buys the company a chance to kick the problem down the road.
With that said, it's not impossible to build a major popular piece of technology within a small company (Joyent and Node.js being a good example), it's just harder.