Not all of us are in a situation where we're iterating through the JavaScript new hotness every couple years and still have significant legacy systems to maintain and support.
I pulled in moment.js 5 years ago for a suite of state death and birth certificate registration apps we are working on.
Due to the amount of “business logic” and small staff size on these, they take years to roll out. I appreciate that this library will “hold still” for a few years.
Not all of us are churning out a new e-commerce app every 3 months. E.g. we replaced the birth certificate app from the 80s, and I expect some version of our app to be around for at least a decade, albeit with patches for new browsers on the front end and new Java app servers on the back end.