The link you posted explains exactly why they threw it away. You may disagree, but the stakeholders did not.

Yes, I know. And I know iXsystems folks too. If you want stable, battle-tested ZFS, Solaris is the only supportable option on Sun hardware like the good ol' (legacy) Thumper. OpenZFS isn't tested well enough and there's too much hype and religious zealotry around it. For person use, it's probably fine for some people but, at this point, semi alternatives such as xfs and btrfs [thanks to Meta] have billions more hours of production usage.