In it's current state, you can't (in a practical way) run LXD on a host os other than Ubuntu. So, using LXD means migrating away from whatever host os you are using, and switching to Ubuntu. That's not trivial.

Over time, as each distro catches up with the same patches/kernel version/etc choices ubuntu made, this problem will go away. For now, however, LXD means Ubuntu as the host os.