[zfs] root mountpoint

[Anton Sayetsky]

Hello,
I decided to install FreeBSD on ZFS root. In almost all guides i saw
the following recommendation:
zpool create -o altroot=/mnt zroot /dev/${device}
zfs create zroot/var
zfs create ...
...
zfs set mountpoint=legacy zroot
zfs set mountpoint=/var zroot/var
zfs set mountpount=...
...
reboot

So we're setting mountpoins for all first-level childs of zroot.

Why just don't use the following simpler setup, when mountpoint set only once:
zpool create -o altroot=/mnt zroot /dev${device}
zfs set mountpoint=/ zroot
zfs create zroot/var
zfs create ...
...
reboot

I've tested both ways, the second also works perfectly but requires
less commands to enter. Can anybody explain me why I can't see
recommendations to set mountpoint=/ for zroot instead of
mountpoint=legacy?