Isn't brtfs itself just a ZFS-inspired filesystem? If that can manage to find a foothold, why can't this?

The only thing btrfs took from ZFS was the featureset - COW, data checksumming, snapshots, multi device. ZFS was a much more conservative design, btrfs is based on COW b-trees (with significant downsides) and if you can put it in any lineage it would be Reiserfs.