There are two massive reasons why js got here, with a million packages for tiny things and a culture of using them: browser cross-compatibility requiring complicated workarounds for easy-seeming tasks, and the introduction of promises + async/await to node.js after the standard library already used callbacks.

When you combine those together you end up with a situation where "normal" js code not from a library can't be trusted on the front end because it won't work for x% of your users, and offers a clumsy API on the backend that you'd prefer be wrapped in a helper. Developers learnt that they should reach for a library to e.g. deal with localstorage (because on Safari in private mode the built-in calls throw an error instead of recording your data and discarding it after the tab closes) or make a HTTP request (because node doesn't support fetch yet and you don't want to use the complicated streams and callbacks API from the standard lib) and they propelled that culture forward until everyone was doing it.