It depends on the project, and we do contribute upstream to other things all the time.
My comment wasn't so much about the overhead of collaboration, but of the chance of there being significant differences in opinion, leading to a place where we'd basically have to fork anyway. Remember, in this specific context, we're talking about an operating system and hypervisor that are core to our product, and we're building our own hardware.
You can't get one single answer for these questions for the entirety of the open source community. Even cross-language norms can be different. These things are inherently tradeoffs.
My comment wasn't so much about the overhead of collaboration, but of the chance of there being significant differences in opinion, leading to a place where we'd basically have to fork anyway. Remember, in this specific context, we're talking about an operating system and hypervisor that are core to our product, and we're building our own hardware.
You can't get one single answer for these questions for the entirety of the open source community. Even cross-language norms can be different. These things are inherently tradeoffs.