That knowledge is becoming increasingly low level though as we build further abstractions over it. If you're working on a network you probably aught to know how TCP works, or at least know how to use Wireshark and a reference. If you're trying to spin up a simple webapp on AWS, you can pretty much stop thinking about firewalls and networking once you set up security groups/NACLs/policies/etc and confirm you can hit whatever is behind them. With new trends like immutable infrastructure coming into vogue, I'd even argue that system administration altogether is becoming a more niche skillset.