You're right that Tailwind throws away the cascade, or at least enables developers not to have to think about it (under the hood, Tailwind 4 uses pretty modern cascading features like layers), but people aren't reaching it because of a lack of understanding, they're reaching for it because as front-ends get increasingly componentized, the cascade becomes less and less of a benefit and more of an obstacle to be worked around, and something that gets that obstacle out of the way becomes more attractive.