It is not nearly as pervasive but there are BSDs used in embedded devices (or more commonly, IT "appliances"). Neither of you have offered an actual counter example - such as a BSD/Apache/MIT licensed software that was ruthlessly exploited or that died off because no one would share their code. In fact my experience has been that communities using those licenses are also very open to sharing and they are thriving in that environment.

Good grief. Which have not been exploited? All unix derivatives came from the same set of (originally open) base code, they shared nothing. They all died (to first approximation). All TCP implementations in the early days were copies of the BSD code. They shared nothing. Does Apple contribute back to Mach or BSD the stuff they do with Darwin for iOS? Does Microsoft publish their modifications to their BSD-derived networking stack?

Can I get a buildable kernel tree for my Android phone? Yup.