Me neither, but the risk is there and well documented.
The point was, ZFS is not great as your normal laptop/workstation filesystem. It kind of requires a certain setup, can be slow in certain kinds of workflows, expects disks of same size and is never available immediately for the latest kernel version. Nowadays you actually can add more disks to a pool, but for a very long time you needed to build a new one. Adding a larger disk to a pool will still not resize it, untill all the disks are replaced.
It shines with steady and stable raid arrays, which are designed to a certain size and never touched after they are built. I would never use it in my workstation, and this is the point where bcachefs gets interesting.
Ted is the maintainer of ext4 and there are not many people in the world who understand this code.
For Rust to succeed, it has to get the subsystem maintainers to agree. It is going to be many years of petting very angry bobcats...
And that is not even the worst I've heard, makes you a bit numb if you follow LKML.