That "basically" is doing a lot of heavy lifting.

I don't even use Tailwind and I know the point is to localize basic style information and reduce the amount of weird CSS you have to write via functions and utilities.

Especially because Tailwind came well before CSS started natively having these features (let alone them becoming baseline widely available).

Both of those goals definitely help the current era of agents by making it easier to find the rules that affect an element without needing to reliably search all of the project CSS, and reducing required context use and the need to keep track of selector lists.