The FOSS contributions from companies mentioned is only at the kernel level. And a lot that use the kernel, but with proprietary blobs for their hardware. I suspect that is because kernel/embedded development is hard and costly.
Most of the dominate OSes people use, with the exception of Windows, is based on an FOSS kernel, with then the layers above and applications being proprietary.
These software systems are being used to lock people in to the specific platforms and perform user hostile behavior. So while having the kernel be FOSS, it doesn’t result in user freedoms imagined by FOSS, it just companies reducing their costs.
There’s some truth to it. I’ve seen devs not clarify something from the designs with other stakeholders due to lack of social skills. You end up with something they implemented to the spec, but makes no sense it reality.