Things like "ZFS needs 1GB of RAM per 1TB of storage" and "it requires that RAM to be ECC" were once common to find online.
These sort of thing seemed to lead to widespread beliefs that it was inefficient, expensive, and fragile. None of that is true, of course, but folks might remember and believe these myths and conclude that it is (or was) bad.
(But it's pretty excellent. I've been using it for about a decade, now. It'd be nice if it fit into the Linux kernel better, but I manage anyway.)
source: used to work for a storage vendor that was marketing a NAS based on ZFS and got credible threats from Netapp to the point that we sought a partnership with Oracle that included indemnification under Oracles settlement with Netapp.
* https://www.theregister.com/off-prem/2010/09/09/oracle-and-n...
* https://www.computerworld.com/article/1585889/opinion-patent...
NetApp originally sued then-independent Sun in 2007, and Sun counter-sued.
Free/TrueNAS/iXsystems has been offering ZFS-based solutions for many years now, and I haven't heard NetApp going after them:
Maybe he was ... they do that sometimes.
I looked around a little. the C&D from Netapp was in ~July 2010 and the partnership and product with Oracle in the Fall (Around the cease fire) and we continued with that (via the Oracle Partnership) through 2011-2015 when the company ran out of cash and laid us all off.
I was just a lowly support engineer so not privy to all the legal details that the executives were dealing with. I too had to just take them at their word.
ETA: I searched a bit. Here's a link
https://www.enterprisestorageforum.com/networking/netapp-thr...
Maybe threats were enough? I certainly wouldn't want to test it myself.