Sort of defeats the purpose of Dev ops, if you have a Dev ops team and a Dev team, doesn't it?
Dev Ops is focused more on operations (tooling around releases, monitoring, etc) as well as doing initial triage for system problems to figure out where the problem is, and if they can't fix it themselves, determine which engineering group can help resolve an issue. Most of the Devops staff does development, but more around operational needs, product features are implemented by Dev.
Dev Ops means different things to different companies.
That said, there's a need for a way to divide the industry between traditional ops people and those with the ability to handle modern infrastructure and develop custom tooling where needed. And for better or worse the industry has decided that "devops" is going to be the way to determine that. Now the problem is all of the fakers (both individuals and teams) adopting the moniker. So now we're back to square one and we actually need to evaluate people and teams based on their knowledge and skill.
Our devops team sits in on design and code reviews to help ensure that operational needs are met early on in the process, and we'll change code to fix bugs or support operational needs. We're not full developers and won't rearchitect entire systems, but we will do bug fixes when we can.
So now we're back to square one and we actually need to evaluate people and teams based on their knowledge and skill
Have we ever left that square?
You're right that every org defines devops differently but it's totally and unashamedly coopted from a movement which, despite being very generally defined, defines it radically differently. And that's not to say it's always a bad thing either. Sometimes it takes a title to help signal change and make an organization better which in the end accomplishes the goal of the movement.
And I agree, I don't think we ever left that square and we never will. But if prepending "dev" to "ops" wasn't at least somewhat effective in getting something out of people in decision making positions it wouldn't be tacked on to job titles and team names left and right. So at least some people think the marketing terms in a job title are a meaningful shortcut even if smart people like you know better.
But ultimately, the developer is the one that best understands how their code may break so he needs to instrument the code accordingly. And when the developer knows that giving the right information to Ops may avoid a 3am phone call, they have good incentive to do so.
Which is why developers need to be on call, otherwise they don't build operational support into apps (monitoring hooks, useful logging, etc)
At my company devops is primary on-call, with a developer(s) as backup, if devops can't fix the problem quickly, they escalate to the developer. If they can't reach the developer or the developer can't fix it, then the entire release is rolled back and then the developers bear the brunt of the release schedule changes.
Without developers in that loop, it's hard for devops to get the tools they need to diagnose and fix problems.