DevOps only failed in that so many don't know what it is.

DevOps isn't a tool, but there are lots of tools that make it easier to implement.

DevOps isn't how management can eliminate half the org and have one person do two roles, specialization is still valuable.

DevOps isn't an organization structure, though the wrong org structure can make it fail.

DevOps is collaboration. It's getting two distinct roles to better interoperate. The dev team that wants to push features fast. And the ops team that wants stability and uptime.

From the management side, if you aren't focused on building teams that work well together, eliminating conflicts, rewarding the team collectively for features and uptime, and giving them the resources to deliver, that's not a DevOps failure, that's a management failure.