that's a great observation. previously to (finally) trying Tailwind for the first time, I would write utility CSS classes to handle those cases like a stack or grid and it worked great building alone. Unfortunately, CSS is really hard to do with others, especially in a big team. Classes always added instead of using the existing one, nothing ever cleaned up. Tailwind is nice in that you get all the power of CSS, just a bit more ergonomic of an API. Plus using it really is just using CSS, just with all the possible utility classes already made for you!
that said i do like to still use classes like "btn" to consolidate a bunch of styles. I think it was a mistake for TW devs to discourage that pattern for so long.