> … why should anyone else? …

Check out the use cases and testimonials:

https://freebsdfoundation.org/freebsd-project/what-is-freebs... https://freebsdfoundation.org/about-us/testimonials/

If you wonder why the first of those two pages is entirely rewritten: see what's going on with the Enterprise Working Group.

https://wiki.freebsd.org/EnterpriseWorkingGroup

Please note, that group's work is necessarily focused. There's a definition of 'general purpose enterprise server', and so on.

Other groups have focii that differ from, or overlap with, general purpose enterprise server. Most obvious: desktop and embedded.

HTH