Distros should not include filesystems that aren't in the kernel in their official installer. Fedora made the right decisions with btrfs. If users want zfs they don't need the official installer for it.
btrfs and zfs are.. not comparable.
It's supposedly meant to "just work" but out of the box it did not. Which is a very common story with ubuntu sadly.
Ubuntu ships ZFS module in kernel package and it works without having to be compiled nor it needs header package.
But more importantly, missing ZFS support should not brick the filesystem. The new kernel just can't mount it, which can be overcome by rebooting to an older kernel. And then addressing whatever the issue is.
# dpkg -L "linux-modules-$(uname -r)" | grep zfs.ko
/lib/modules/5.4.0-70-generic/kernel/zfs/zfs.koIf you use DKMS, then you might have issues, but there's no need with Ubuntu (and other distros like Manjaro) anyway.
Btrfs is probably never the right decision - use the FS that's right for you and your workload.
And you're posting anti-btrfs FUD.
https://lwn.net/Articles/824855/
https://facebookmicrosites.github.io/btrfs/docs/btrfs-facebo...
Even if it's the only deployment in the world, it's more than "never". They provide strong technical reasons for using it.