There's `space-y-N` which does exactly this, `space-x-N` for horizontal.
What do you do with that snippet when you realize some elements arbitrarily need more or less spacing than others because the designer decided it looks better?
Repeating yourself isn't the end of the world, and on occasion DRY is worse (look up incidental duplication).
Even after optimizing Tailwind. You still end up with way more css than you should have. Add all the classes in the HTML and you're sending users a massive amount of data.
Instead of writing:
you write `mt-100` a thousand times.