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).

For context, we use this in production: https://www.npmjs.com/package/ical-generator, but again that's NodeJS

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.