Control is important. Apple has never had to fight with Torvalds or IBM or Microsoft over getting something added to the kernel. Just look at the fiasco when Microsoft wanted to add a driver for their virtualization system to the kernel.
Also, one thing you'll notice about big companies - they know that not only is time valuable, worst-case time is important too. If someone in an open-source ecosystem CAN delay your project, that's almost as bad as if they regularly DO delay your project. This is why big companies like Google tend to invent everything themselves, I.E. Google may have "invented Kubernetes" (really, an engineer at Google uninvolved with the progenitor of K8s - Borg - invented it based on Borg), but they still use Borg, which everyone Xoogler here likes to say is "not as good as k8s". Yet they still use it. Because it gives them full control, and no possibility of outsiders slowing them down.
Also, one thing you'll notice about big companies - they know that not only is time valuable, worst-case time is important too. If someone in an open-source ecosystem CAN delay your project, that's almost as bad as if they regularly DO delay your project. This is why big companies like Google tend to invent everything themselves, I.E. Google may have "invented Kubernetes" (really, an engineer at Google uninvolved with the progenitor of K8s - Borg - invented it based on Borg), but they still use Borg, which everyone Xoogler here likes to say is "not as good as k8s". Yet they still use it. Because it gives them full control, and no possibility of outsiders slowing them down.