Because Tailwind is often suggested as a way for novices to implement design without having to really learn CSS. Simultaneously, allows people who don't care at all for CSS or design to create something functional.

Tailwind does not require knowing CSS. It'll get you around tailwind faster if you do know it, but you do not have to care about what Tailwind is really up to when adding "outline outline-2 p-4 outline-offset-2". This is a major reason why people pick it up in the first place, to ignore CSS as much as possible.