I worked in the home office of WalMart Stores, the retailer, from the mid 90s until 2009 as a hybrid network engineer/developer. That is, my team worked in Network Engineering, but we wrote tons of code, because when there are millions of different IP addressable nodes on a centrally managed network, there will be code to manage it. (:

In that era, I think WalMart handled this apparent developer/sysadmin confliact quite well. Believe it or not, even though we (the whole company) had exceptional uptime, we were also extremely agile. LOTS of code was written and rolled out across thousands of sites, multiple times a day.

There were a number of keys to this, and I'll enumerate a few.

1. Most new hires (those that had minimal previous experience) to development positions had to spend their first six months working at one of the four or so major help desks. Note: they were paid their target salary, but in an hourly fashion.
2. The various operations teams had complete and final say so over what went out, and how incidents were handled. A couple of the big operational areas were Unix Operations, Network Operations, Windows Operations and Mainframe Operations. I called them 'teams' but each had a number of teams, and their own help desk.
3. Any time there was an impacting problem associated with a program developed by team X, a war room was called by the relevant operational area. A member of team X (a developer) had to stay in that war room (switching off between team members if it ran very long) until the production problem was not only fixed, but also deemed unlikely to recur, except in cases where that dept of a fix would take a long time.
4. Every development team had a pager rotation, with rigorous expectations about responding to such pages. This was primarily to support the previous point.
5. Because of the enormous operational scale, all of the major operational areas had dedicated teams focused on automation. My team was that team for the networking area. Furthermore, most of the rest of the operational folk read/wrote code to some extent.

In short, incentives were aligned. Teams that wrote externally facing code felt pain if the stuff they wrote and released caused problems. Operational folks wrote/managed/interacted with tons of their own code in order to manage the enormous infrastructure. Also, ops folk were far more willing to let things move with velocity knowing that the people who actually wrote the code would be required to support it, globally, any time of the day or night.

Another, perhaps even more important reason we were so successful during those years (and the years before) was a strong and vibrant esprit de corps. The entirety of Information Systems was, at the time, around 2000 people, and we were facilitating double digit year over year growth over a 150 billion dollar company. We had over 5000 remote sites in 15+ countries, with a diversity of software and infrastructure that was honestly pretty astounding. Each of those sites had quite a surprising amount of infrastructure.

We worked hard, and we produced huge velocity with fantastic uptime. For example, the network achieved six 9s of availability a couple of quarters.

In end, while things were sometimes contentious, we trusted each other, and only minority of teams were forced to work bad hours for any length of time.