DevOps failed because management never really understood that it needed to be a dedicated team, and that it shouldn't just be a little vassal state of the ops team, nor is it just "backend devs who know ops" who keep getting pulled away from devops work to do backend work.

IF DevOps had been allowed to thrive, we could have eventually reached the holy grail: A Heroku-like environment that developers can use to run their apps. Instead, we stopped short in the no-mans land of k8s, helm, AWS lock-in, terraform, hashicorp, red hat, azure, not to mention tons of spreadsheets owned by the ops team that developers must beg and plead to get changed.