People are reluctant to use openZFS on Linux as it can't be included in the kernel due to license issues. I'd still say it has widespread adoption when you consider the people willing to run it on Linux and how popular it is on FreeBSD/some other systems.
I think that certainly hurt it. Also, when Oracle bought Sun, they started restricting Solaris use to Sun hardware only. Previously, we were happily using Solaris 10_x86 + ZFS on SuperMicro boxes.
We still have north of 7PB of ZFS-based storage at $DAYJOB (NexentaStor based and Dell hardware) after introducing it nearly eight years ago. ZFS itself has been awesome.
