In fact, not all languages have a library as simple as the Node package you are pointing at. Most libraries require you to use the iCalendar standard syntax which, for a single event, is accessible but becomes complicated for a recurring event for example.
But for the Node package you mentioned, you are absolutely right.
Just out of curiosity, can you name one such language that doesn't have a library for generating/parsing iCal? (I assume probably the language you use for your product).
I work mostly in PHP, and when I started this project, most of the libraries were very incomplete. Customer needs led me to develop a more complete library and it's only recently that I proposed this library as an API. But, yes, much more complete and easy-to-use packages have appeared since then, although they still focus on events and don't allow to manage tasks or notes.
But for the Node package you mentioned, you are absolutely right.