Well one reason could be that you are a commercial company and you make a proprietary appliance. FreeBSD's license (3 clause BSD) is way easier in that case then the GPLv2, let alone GPLv3 (which a lot of userland is licensed in most Linux distro's). Examples of some high profile appliances running FreeBSD: Sony's Playstation 4 and Juniper's Junos OS which runs on their firewalls and routers.
Ubiquiti is getting a lot of flak for not being GPL compliant and the only thing I can think of when I hear this is: "Why did they use Linux if they wanted to make a proprietary product? They wouldn't be in this mess if they had used FreeBSD.".
Another reason could be FreeBSD ships ZFS out of the box because combining the CDDL + BSD licenses is not a problem. However GPLv2 (Linux kernel) + CDDL is a problem.
Any other use cases other than licensing that would make somebody want to use *BSD instead of Linux/Mac?
I've used FreeBSD on my production systems instead of Linux since I started this whole bit 15 years ago. Linux surprises me. FreeBSD, for example, does not. I do not walk away from production FreeBSD systems and have them fall over for reasons other than hardware failure. Full stop.
I would like to gain understanding as to why the BSD maintainers + developers invest the time they do into their projects. They are awesome projects, but... who are they for? The 0.1% of people who lie to themselves saying "FreeBSD makes a great desktop/laptop?" Mac OS X makes a great laptop, that's why it is in every coffee shop around the world. Linux must beat BSD server usage 10:1, if not 100:1. I'm sure somebody below will prove me wrong but I strongly feel it's just the echo chamber effect of reddit/Hacker News. I can't think of any good reasons somebody would use *BSD over Linux and "their man pages are great + the clib is written in the same repo as the kernel + userland utilities" isn't good enough of a response for me.