That was certainly not overnight. The biggest disruption they personally did was offering a better alternative to Bootstrap. More customization, JIT compilation that allowed for custom class interpretation without any added CSS, proper flex consideration, removing unused library classes in the production compilation step, etc.
Beyond this, you should really be thanking things like Shadcn for the “date picker disruption”. It is a component library which arguably could’ve existed without Tailwind ever existing.
why shadcn and not bootstrap? shadcn is like a cool weird approach to a ui kit but bootstrap got us a date picker iirc.