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And why wouldn't you want to do that? Why another OS? Why another distribution of Linux? Why a fork of this or that?
You post a comment on a site that is (at least partly) dedicated to post news about the myriad of operating systems in the history of computers, and you question why would anyone want to port a specific userland to another operating system? It's what people do!
Alot of people chose FreeBSD over Linux, me included. It's called personal preference and one should always respect that in the end. The more choice in the world the better!