

ZFS is not really hip. It’s pretty old. But also pretty solid. Unfortunately it’s licensed in a way that is maybe incompatible with the GPL, so no one wants to take the risk of trying to get it into Linux. So in the Linux world it is always a third-party-addon. In the BSD or Solaris world though …
Also ZFS has tendency to have HIGH (really HIGH) hardware/CPU/memory requirements.
This is twelve years old, but it nicely illustrates what BTRFS (and ZFS on other OS) can do … https://youtu.be/9H7e6BcI5Fo?t=206