I work in what is increasingly a pretty different sysadmin environment
I've written before about what our sysadmin environment is like but that description doesn't really convey how and why our environment is increasingly different from what the rest of the world seems to be moving to, with the resulting very different needs. Today I'm going to describe our environment from another perspective.
In our environment, we broadly do three different things as far as computing goes. First off, we provide a number of standard services to people in the department, things like Samba file service, printing, email with IMAP (and webmail), DNS, and so on. This sort of internal service provision is probably still quite common in reasonable sized organizations (trendy ones have no doubt outsourced it to GMail, Dropbox, et al). Users are not exposed to the backend details of what software stacks power these services, and although our current stacks are stable we have shuffled them around in the past and could in the future. We definitely feel no need to run the latest and greatest software stacks and versions, and generally prefer to leave these services alone for as long as possible (this too is probably common in organizations doing this).
Second, we provide general multiuser computing to our users in several forms (general login service, compute login service, and various forms of web service ranging from plain HTML pages through completely custom web servers that they run). Naturally, how people use these services and what they run varies widely; we frequently get requests to install various bits of open source software that people want, for example. Our users obviously are pretty exposed to what OS and software we're running, and we couldn't make significant changes in it without serious disruption (even mild changes like Ubuntu version upgrades can be disruptive). Our users also care a fair bit about having current or relatively current software in this environment (for a wide variety of open source software). My impression is that we are one of the few environments left that provides this sort of computing.
Finally, the large collective we run a certain amount of custom services and applications, both for people inside the department and for people outside it. Some of these services are developed by the same sysadmins who run the hosts they're on, but others are increasingly going to have separate developers and sysadmin people (these are generally the complicated applications). Users of these systems aren't exposed to the backend details, but obviously the developers are since they have to write code for some deployment environment. The developers probably care (to some extent) about working with commonly chosen environments (eg Linux and Apache) and with current or reasonably current versions of things like databases, web servers, and so on. This sort of thing is closest to ordinary 'operations' or 'devops' work in the outside world but is generally less demanding for various reasons (there is very little here that could be described as 'business critical', for example).
(I wouldn't be surprised if some day we wind up with developers who want to deliver their applications as Docker containers or the like, rather than dancing around with asking us to set up a database this way and an Apache/PHP web environment that way and so on.)
So far, nothing in our environment faces high load or high demand, neither in our standard services nor our custom services. When unusual surge demand descends, so far it is not really our problem; we have some responsibility to keep the overall system up and responding, but very little to make sure the specific service affected does not collapse under the load it's experiencing.
In theory we could run these three different sorts of environments using different operating systems and software stacks. In practice we have limited staff and so the needs of the multiuser computing wind up spilling over to affect what we run for the other environments; provided that it works reasonably well, it's simply less work to have a uniform setup across all three environments. Today most of that uniform environment is Ubuntu LTS, because Ubuntu LTS remains the best environment for providing the multiuser computing part of things.