If you want to know what to learn, learn web fundamentals. Learn the Web APIs and everything that's been standardized in HTML, CSS and JS. Learn relational databases. Etc. Learn how to build your graphics using SVG. Learn how to do your animations with CSS. Hell, if that's too boring learn WebGL and WebAssembly. They may not be ready, tested or in vogue, but they'll be here for the long haul. Screw libraries that abstract over this stuff. If you don't learn from the ground up you're putting your future career in the hands of things that may end up being ephemeral. Stuff like React, Sass, D3 etc might seem like safe bets, but so did jQuery at one stage.
Just, be aware that your goals as a developer are sometimes at odds with the goals of your employer or even the community as a whole. There's a lot of pressure to get up to speed and be productive as quick as possible. You can see this in things like the React docs, which encourage you to ignore language features and just memorise patterns.
But I want to get stuff made. I have ideas, I have a thing I want to make. Would I like to really deeply properly fundamentally understand JavaScript? Sure! Do I have time, with my actual real job and friends and life and other hobbies? Nope. Thank goodness, then, for React. It's a godsend.
(Also, I have no desire to "work" as a developer for someone else as my salaried job. Perhaps that affects my outlook.)
My usual measuring stick is "if this thing disappeared tomorrow, would I be able to recreate it from scratch myself with no documentation?" (obviously not up to the same performance standards).
It's still a long way off disappearing and in many high security environments might be the only approved library.
Yeah sure, I know a bunch of stuff on that list. SemVer? Yeah, I get what the numbers mean. I google the ^x.x.x syntax, whatever.
ESLint, Prettier, yep, install and drop a .config file somewhere. Copy someone else’s. It’s hardly rocket science.
Webpack, I know that it exists and as soon as the defaults installed by create-react-app break, I’ll figure it out.
This is a big list but let’s not pretend that you need to be an expert in any great amount of it to get something made. And the purpose is right there at the top:
“The purpose of these roadmaps is to give you an idea about the landscape and to guide you if you are confused about what to learn next and not to encourage you to pick what is hip and trendy.”
I think it does that pretty well. Settle down a bit, everyone.