Because Linux is the dominant OS on servers (so my dev environment can match the prod environment,) has way more tutorials,and documentation and also has way better hardware support.
I'll agree on the rest, but more docs != better docs; BSDs tend to ship complete manpages without needing to wade through a hundred blogposts (half of which are out of date or slightly wrong).
The original package maintainers could write instructional materials that start from the errors, but I suspect that's too hard. Without specific training, it'll always be easier for third parties to provide ad hoc than first parties to produce as part of release.