At a time, it was the default, and you had to go out of your way to use /dev/disk/by-id (you had to create your pool, export it, and then import it by id), only to be hit by another issue, where when preparing grub, it was looking for the IDs straight in /dev (that's how I learned that ZPOOL_VDEV_NAME_PATH=YES exists).

Yeah, putting / on zfs was not smart. Nowadays, when the distro doesn't support it out of the box and doesn't come with kernel+bootloader+zfs tested together (i.e. proxmox, ubuntu), I wouldn't do it.

This was last year on Ubuntu.

I assembled the zfs array using by-id, but after a reboot zfs reports the drives as being on /dev/sdx.