I've been writing CSS by hand since the late 90s. I resisted Tailwind for a long time, but I tried it on a pet project and I get it now. It doesn't fundamentally do anything that you can't do in CSS already, but it sort of "quantizes" the DX such that the vast majority of the CSS you'd usually end up writing boils down to a set of conventions.
You can still write your own CSS as needed (and probably should, for some of the more esoteric Tailwind cases), but stupid stuff like flexbox directives and padding/layout that you do literally everywhere become a lot easier, especially with things like the Tailwind VSCode plugin which provides autocomplete, reflection on defined variables, and linter errors for duplicated or incompatbile expressions.
Right but it comes after a long line of similar CSS frameworks with the same promise, starting with Bootstrap, and there were large movements about 10 years ago of whole orgs deserting those frameworks because of serious issues. Are you saying Tailwind somehow has resolved those? That was the main reason I didn't try to learn it considering it to be just yet another CSS framework's conventions.
Tailwind solves a somewhat different problem. It's maybe easiest to think of it as a bunch of aliases for writing inline styles. The fundamental problem with CSS at scale is leaky abstractions, right? Tailwind moves the abstractions down a level, so that rather than attaching semantic classes, you're just composing the properties of an element directly, except you don't have to remember if you used px or rem for this padding, or what the media query for a mobile breakpoint is. This tends to reduce the incidence of high-gravity classes which tend to accumulate features, at the cost of some verbosity vs something like Bootstrap, though it's significantly less verbose than equivalent inline styles would be.
You can still write your own CSS as needed (and probably should, for some of the more esoteric Tailwind cases), but stupid stuff like flexbox directives and padding/layout that you do literally everywhere become a lot easier, especially with things like the Tailwind VSCode plugin which provides autocomplete, reflection on defined variables, and linter errors for duplicated or incompatbile expressions.