Sure, but to be fair, I've met plenty of back-end developers, even senior ones, who don't know the intricacies of DNS, certificates, OS, etc. It's best to recognize the domain is enormous and a lot of folks have a desire, or arguably a requirement, to specialize.

I'm reasonably certain that if we created a union of all of the topic sets that HackerNews commenters identified as requisite knowledge to be a software engineer it would take a lifetime to plow through.

Like putting together a winning baseball team, it's best to recognize that your team wins when you put together a group of contributors that contribute their specific honed skills.

"Try to learn something about everything and everything about something." - Thomas Huxley