There are a lot of comments to the tune of "why does a CSS library need 1m+ (or any money at all) to survive?". I'm no expert on this kind of thing, but Tailwind 0.1.0 first released on November 2017. Since then, there's been continual improvements up until last month with 4.1.18, totalling 8 years of dev work. A simple CSS library wouldn't have much need to go past 0.1.0, certainly not 1.0.0. Clearly tailwind did, which would imply there's more than meets the eye.

But you can't have it both ways, it can't be just a simple CSS library that doesn't need that much money, but also expect a decade of work+ on it. After all, this originally stems from the fact that a PR attempting to improve something didn't get merged in; a technically finished project would have the same problem, but that would be the rule rather than the exception.