- It's easier and cheaper to find Linux sysadmins than BSD ones
- There's more commercial software supported on Linux
- There's more companies offering support for Linux
- Linux is more portable than BSD
- Linux is one of the standard server OS offered by providers, BSD isn't
that's the big one there. My favorite, Hetzner (not only mine, they have a ginormous amount of dedis) offers BSD but a) not all servers are compatible and for older servers you can't even know whether they are without booting into Linux first b) it's much more of a hassle like installing Linux gives you a ready-to-go system while the BSD install needs tweaking with sysctl and network both.
I'm surprised that more embedded devices don't run some sort of BSD because they wouldn't have to release code. The PS4's OS is FreeBSD, which they did release a lot of code in return, but they don't have to open source or release all their code (i.e. DRM and other "Security" based stuff) if they don't want to.
Linux has had a ridiculous amount of work from a variety of sources in it's drivers. I once used a git animation tool (forget the name of it, sorry) on the linux kernel source, and the area where the drivers were put was buzzing like a beehive, as people from all sorts of companies were making sure their stuff was supported on linux.
Probably Gource I would imagine http://gource.io/
Linux runs on all these platforms and more - that toaster only had an ARM board sticked to it
And that is a 2-way road, where some people cry on forums and maillists anyway, that companies tend to use BSD and not return to community. There is no need to paint it as a win-win situation(distribute proprietary derivate software) when it clearly has its problems too.