To me, old fashioned means sticking to semantic principles and separation of concerns.

(P.S. get off my lawn)

I can only imagine what you think of TailwindCSS so...

Counterintuitively, I'm okay with it .. but just because it solves problems I see as more important than purity in the codebase.

Large FE projects often have multiple developers, which come and go .. and have differing levels of ability.

Tailwind provides a framework that's easy to jump into, provides consistency and is widely known.

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However, that doesn't mean I can't think this particular technique isn't a good idea.