This is a genuine question: are Tailwind fans really saying you don't need to learn CSS? I'm a huge Tailwind fan and I've not seen people say that. I actually don't even know _how_ you could use Tailwind without knowing CSS!
It's like you can know how to unclog a toilet or change a faucet, you're no plumber, you don't know what a plumber does, but you can do enough for 80% of your needs, and when you can't you either call the plumber or you pick up a plumbing book or go to google/youtube.
I don't think you need to be a CSS expert to use tailwind, that's why I stuck w/ bootstrap for so long, but I also think you need to maybe think more about the underlying css so at least be willing to keep more CSS knowledge in your RAM or SwapFile in your brain, but there's things like daisy-ui that sort of wrap TW in bootstrap like niceties so you can kind of have both worlds, and come with nice themes to boot.
All arguments I've seen are about consistency and maintainability.
OT: I often see someone make a dubious claim, someone else asks for proof, and they say "that's what I keep hearing on Twitter."
It's just another logical fallacy, especially since Twitter is known for bad and hot takes.
It doesn't support your argument the fact that you heard a random person on social media say something dubious.
/rant
Personally, I usually just look through component sites for something like I want, then modify it to my needs. 95% that works, sometimes I go build it out myself.
I'm fullstack, but more backend and that's where I'm most comfortable so the less I worry about design the better it is for my sanity, except I do like dabbling w/ the js layer in vue, alpine, or react.