Having a smaller user base than the world's most used kernel (Linux) doesn't mean it has a small user base in absolute terms. And being a smaller kernel in lines of code is certainly a positive thing.
This pattern repeats, with OS's smaller than FreeBSD having good reason to be chosen in production.
Fun fact: Apple used NetBSD on their Airport product series.
OP didn't say FreeBSD was bad in my reading, but as a somewhat irregular user you just notice 1000 papercuts (which are not the OS's fault per se for the most part) but which detract from the overall experience. Every nth software package you use for the first time needs a (small, 3-line) patch which is mostly because the people develop on Linux. Sometimes it's better if they develop on OSX, sometimes it doesn't matter.
FreeBSD isn't run on a limited choice of hardware.
> Today, FreeBSD is used by many IT companies such as IBM, Nokia, Juniper Networks, and NetApp to build their products.[16][17] Certain parts of Apple's Mac OS X operating system are based on FreeBSD.[18] Both the PlayStation 3 and Nintendo Switch operating system also borrow certain components from FreeBSD,[7][8] while the PlayStation 4 operating system is derived from FreeBSD 9.[19] Netflix,[20] WhatsApp,[21] and FlightAware[22] are also examples of large, successful and heavily network-oriented companies which are running FreeBSD.
And hint, that's why the playstation etc has "just" parts of FreeBSD....they don't need tar and llvm in it.
Your comment makes no sense in that regard.