The thing I find weird about big companies failing to support open source projects that they use (e.g. ffmpeg, which is in the news at the moment) is that it's in their selfish commercial interests to fix bugs etc.
It's also good marketing for some customers, and a recruitment tool (some of the best devs prefer jobs where they get to spend at least some time on open source).
I get companies not being altruistic, but there's a strong argument for supporting open source with cash / engineers.