date-fns dependency

[AleksandrTermenzhy]

Given that the main feature of the library explicitly depends on date-fns, I wonder if there any downside to putting it as a direct dependency instead of a combination of dev+peer dependencies?
Doing so would also allow to remove the recommendation in the README to add the date-fns library explicitly to a project.

Additional observations: if someone omits the recommended step of adding date-fns as an explicit dependency, the behavior will differ depending on the package manager used: npm will install the peerDependency, while yarn will not, resulting in a broken build.

To sum up, I would like to know if there is any history behind not putting date-fns as a direct dependency, and if not, are you open to doing otherwise?