I tell my students that you have to know how something works in order to defend it, maintain it and to improve it.
In one of the most extreme ways, when I was working Missile Defense, deployment of updated systems was VERY slow - working on systems that are 20+ years old is very common - because you can get predictability down to the wire level. In other words, O&M would know every signal, every voltage, everything that would run up and down every wire. It was that detailed.
So you knew that if there was an anomaly, you could see it and correct it. Given the need for extreme reliability for systems involved in defense or space applications, knowing how your system worked helps with maintenance.
Now, it brings up the point of why we have SIEMs and SOARs - because no one can know or see it all. Even on the most simplest of infrastructure systems - say, five desktops and one little server, you still have to have a bit of faith in something. IMAO, Zero Trust, while a great goal, isn't completely possible. To me, ZT is like a logarithmic scale - the harder you go, the more expensive, costly, and difficult it gets to actually get there. So you go for a 'good enough' and hope that takes care of you.
With trained IT staff to not understand how the network actually works, to me, is asinine, even if they aren't directly involved in Cyber operations. The thing is, Network+ is not one of the more sexy certifications out there. Everyone wants the certifications that will score big money and Net+, on its own, doesn't command THAT much. Even today, I reckon, CCNA/CCNP has fallen out of favor. Networking becomes to be something you just "do" to get to the next level. In fact, out of the Core triad, I see Network+ requested far less in job listings than Security+ or even A+.
