Is there any actual evidence for that claim?
I'm a Linux guy so my view is probably biased. All I'm seeing is BSD licensed projects being ripped off by corporations left and right. Maybe we mean different things with the word, sharing. Netflix using FreeBSD and their idea of giving back to the project is telling them this will lead to their code being tested really well? That sounds to me like "please create a web page for us for free, it will lead to more exposure for you".
Why does FreeBSD then not have your TLS sendfile code? Linux has TLS sendfile. It was contributed by a corporation, as far as I know.
Personally, I have always really liked the BSD projects. The people working on them have been nothing but professional and yet courteous, they tend to fix their security issues quickly. I would love for them to get paid properly.
With money. Not with "exposure" or "we'll test your code".