Language and Platform
Sometimes when your company gets big enough, it starts to drive the full feature development of a framework or language.
Both GitHub and Shopify employ core contributors to Ruby and Rails teams. This allows them to remove painful parts that reduce productivity of their own engineers, but also give it back to the world through open source.
A recent example can be seen in Rails 6. GitHub has a multi-database configuration, Rails did not support this. GitHub's engineer, Eileen, worked tirelessly with her team to integrate this functionality in the Rails framework. Now everyone gets to use this feature for free and GitHub doesnt have to maintain something that only they use.