Anecdotal as it is, I started my career working as a sysadmin while studying CS. When I was younger I was quite interested in security (e.g. I followed defcon and CVE lists and read a lot of manuals and source code). I built server software, broke applications, and did a lot of reverse engineering. In that time I was forced effectively to learn about how the OS worked and how to utilize it, both Linux and Windows, from C APIs to scripting, package management, and everything else needed to effectively work in those environments, primarily around reverse engineering and vulnerability research.

That experience naturally lead to me becoming a sysadmin during my study at university. It was a fairly straightforward application of what I already had learned with a much larger scale of management. The primary thing I gained out of it was a drive to automate everything. When I started that job most of the sysadmin work was manual, but a few of us spent a huge amount of time focusing heavily on automation and when I left most of the work was automated and we were just doing meaningful firefighting and supporting development.

As an engineer, the main benefits have been understanding how my software is going to run in an actual software/hardware stack, easily jumping into a production environment and debugging complicated issues, being able to quickly have my OS do what I want, and that drive to automate everything. A lot of that informs how I build software and in general it feels like it makes me a lot more productive.