Suppose I plan to assemble infrastructure for some ideal of "Deployment Maturity" - no downtime, any time of day, one-click, etc. But it turns out the development team has designed the software to be un-load-balanceable thanks to in-memory sessions, so, thud goes my big plan. That's a very common problem.
Of course many of us see a "proper" devops discipline as interdisciplinary, so I suppose those folks would tell me to get in there, gently push devs out of the way, and fix that session mgmt problem. Of course I need advanced skills, but I also need advanced permission. Somebody's gonna fight me. Now I'm turning into more of a site reliability engineer.
So the maturity model definitely applies - especially when it comes to security - but when you're in devops-just-means-ops mode, you're much more tail than dog and it seems like you have no choice but to put capability first.
On a tangent, I once drew 2 dimensions and put all our political parties on them. It turned out the "left" and "right" were trending toward "up" and "right" not opposites. Upper right corner was totalitarian BTW.