Why is this package so much smaller than the alternatives?

https://github.com/you-dont-need/You-Dont-Need-Momentjs#brief-comparison

It's several times smaller than all other alternatives (even those with tree-shaking) and seems to be as feature-rich as other packages.

What's the secret ingredient in this package that other packages are not able/willing to replicate?
Just want to understand if there are any drawbacks in using this package.

Start with the linked README's brief-comparison section and compare the package's documented feature set with the alternatives. Done means adding a concise explanation of the size difference and any relevant drawbacks to the documentation, or providing a sourced answer that resolves the question.

Written by the indexing model from the issue text.