There is no size limit on how many features could ship with a library. In fact, we live in an age where packages like rimraff report around 50 million downloads per week.
But the original question, and the point it made,still stand: why isn't there such a library to provide such a feature? Might it be that you're overblowing it's demand and usefulness? Perhaps there is no such thing in the standard library because no one bothers with it, or feels it's missing?