Note that OpenBSD now uses the much smaller doas instead.

Which you can use on Linux however it's missing sudo -e and emacs tramp doesn't work with it.

Sudo -e FILE opens a copy of the file with $EDITOR and then moves copy to replace FILE

Tramp opens a file including present buffer and writes it as root to achieve the same effect.

EDIT Tramp now works correctly for me sudo -e is simple enough to script looks like a winner for simple things when complex isn't required

Yes, but it's still a red herring when discussing the advantages of FreeBSD (or OpenBSD, for that matter) over Linux.