If you are making something that you care about you should probably understand how it works. I didn't know this was such a hot take.
I think the main point is, if you're building frontend web apps, you should probably know how HTML, CSS, and JavaScript interact to some decently high level. Can you look stuff up on the margins via AI, or StackOverflow, or whatever? Sure.
If you're building <something else>, you should probably know the core tools and concepts at the appropriate level to build them.
No we do not need to know every aspect of CPU branch prediction and whatnot to make a webpage.