I mean, they're still super clever, but people learn that stuff by reading about it and practicing. You could go that way too, it's not black magic.
Then why do I have "black magic" on my LinkedIn profile???
I learned web dev first by using Geocities and Frontpage, then Dreamweaver. These days I actually get paid to write Javascript (something young me would've found unbelievable enough already), but to me that's still a huge difference from "real" programming, especially in C or assembly.
Web dev (at least the kind I do) is mostly still just declaring UI in a XML like syntax, then wrapping it up in some events and state management. It's not that different from, say, Visual Basic. At its core it's a bunch of event driven reactions and API calls based on UI clicks. Once upon time that was Perl or PHP or jQuery, now it's usually React, but the fundamental process of "declare UI, add event handlers, send to APIs" hasn't changed much IMO.
But an OS? Man, how do you work with memory access? Overflows? Garbage collection? Device drivers? Caching? Graphics pipelines? USB? Lightning? I don't even know where to start with any of that, and an OS is ALL of that and then some.
Mad props, is all I'm sayin'.
If you want to get a taste of what that means that is definitely 100% within your abilities, try to write a Brainfuck interpreter in JS, and a Brainfuck to JavaScript compiler (that yields a string that you can eval() to run the program).
Then try to write some simple Brainfuck programs, then try to write a Brainfuck interpreter in Brainfuck. At this point you won't yet know how to write an operating system, but you'll definitely know how it feels to write one.
I think I have pretty underwhelming dreams relative to OS devs, lol. I feel a ping of reward when a web page loads without crashing, or a npm audit passes without red, or I finish a level in Mini Motorways.
Generally, my secret to a happy life is to aim low, and then be satisfied once I hit half that :)
Another time, I read a Brainfuck wikipedia entry for about 30 seconds.
I still haven't recovered.
You start much simpler. Grab some ESP32 or ARM development board and start with trivial things on them. Simple devices also have simple drivers - sure, trying to connect to an NVIDIA card is hard, but an 128x128 LCD display is trivial. Then you build more complex things on top of that. Same with PHP - you start with 'echo "hello world"' rather than full reactive page with many server routing endpoints.
Web only started in the 90s, and was intentionally designed to be simple (html and stuff). Even so, it's morphed into a very complex thing already. It doesn't feel like so because you (and to some extent, I too) have been witnessing its evolution as it happens, so it's all incremental, but I can imagine a total newbie coming into the field and feeling overwhelmed.
Like, try to explain things like CSRF tokens, Web Assembly, HTTP/3...
It is black magic to people who read and don’t understand a thing. :|