If you're not a designer, it takes a non-trivial amount of time to add the utility classes you need to get something that looks passable. Quite simply, it gives you too much control over something that just doesn't matter for an MVP.
There are great component libraries out there (I'm a fan of Chakra) that give you sane defaults so that you can get something off the ground, while not focusing on something that doesn't matter at the MVP stage.
Maybe Tailwind + Radix makes more sense after you raise funding...?