I love FreeBSD, I started using it in 1995, one full year before Linux.
Forget about desktop and small servers use. Both for xBSD and Linux, big server and Embedded is where is at. Desktop/Laptops belongs to Windows and MacOS, and Cellphones belong to iOS and Android...
Well, guess what, HW support for Linux is bigger than for xBSD.
In emebeded, every single SoC maker will make drivers for every single SoC component for Linux, for xBSD, well, not so much, some of them will, some of them will not, which makes more onerous for companies the process of choosing both SoCs and ancillary components if they want to use xBSD.
Meanwhile, in Big Server Land, while the architectures are well supported, the drivers for ancillare components, well, not so much. AI cards, HPC cards, 400Gbps Eth, RAID cards.... some do ship xBSD drivers, some do not.
Unless you are spinning VMs (and paravirtualized ones at that), you will have trouble making xBSD play nice with big iron.
And to top it of, unlike with linux, where companies like RedHat, Suse and Cannonical (and oracle and Huawei and...) offer pro-grade support, there are no such backers for xBSD, yes, there are small players, but nothing with enough traction....
Companies big and small would love to use xBSD, because of the license, not to close the source per se, but rather, to avoid all the drama if/whensomeone in the chain forget to publish the sources, so...
Why the do not do it? Lack of support.