Ok, but I've worked with people who are pretty good with web dev, but I guarantee you they don't know how memory gets requested from the operating system.

Like, sure it helps in some contexts, but in their context it would largely be irrelevant.

For the wast majority of people, it's fine for them to know basic tradeoffs between stdlib container types. Most web performance problems today come from misusing tools, whether container types, bad algorithms, memory leaks (and I don't think knowing how an OS manages memory would help them in JS for example), DOM pollution, or oversized assets or whatever. And my take is that that people are often too overworked to care about it, rather than lacking awareness about these things lol

On the other hand, if you're a systems engineer, then you absolutely do needs to know all of this stuff.

And I bet you they'd navigate stuff like better than a systems engineer, because that's more useful to their day to day!