Those all sound like things for a network engineer to know. I’d rather a web developer spend their time mastering the intricacies of CSS than learning someone else’s specialty.
DNS records are usually set once and forget. You read the documentation once when you’re doing it, and then you basically never have to touch it again. I had to look up the difference between a CNAME and an A record, even though I’ve set them numerous times before. Not useful in day-to-day.
DNS servers: going to assume you query a DNS server that has a map of domain names to IP addresses, with basic routing via DNS records, which then resolve to a final address which is sent back. Again, never going to have to know this unless I’m a network admin.
Port-mapping: what is there to understand? I have literally never had to map ports unless I’m port-forwarding a game server I’m running on my local machine, that’s using a router to be exposed to the outside network. Literally, every cloud provider will give you an endpoint address that does not require port-mapping. If you’re setting up a company network you have to port-map, but not if you’re deploying a simple server/app. Ergo, network admin’s job.
Compilers: lol. There’s tons of languages, and tons of different compilers for each language. Then there’s distinguishing compilers, interpreters, compiler-interpreters, and transpilers. At the end of the day they take text (usually) and transform it into another form. I’ve built a compiler before (toy AST & recursive descent), but I have never needed to know about it in a CRUD context.
I'd like to take the opportunity to throw some shade at network admins because out of all companies I worked at, they have consistently been the slowest to respond when their stack is usually the most reactive to changes.
The more people that offload their knowledge to the category that should be handled by networking experts, the higher the backlog for the networking experts. Which kind of supports OP's point.
It depends what you mean by 'deploy', because that could cover everything from spinning up a new box in a cluster to creating a kubernetes deployment to simply dragging and dropping files in an FTP application or using scp.
I’ve been working professionally in the field for 25+ years. I just turn it over to the network and devops teams when it’s time to deploy. There is no reason a web developer should know those things.