Alpine.js really was created for javascript sprinkles, where even vue.js might be overkill. For example, if you have an app, but you need to have dropdowns and modals. Then something like alpine.js can be nice.

So it is actually not intended for things more complex than basic interactivity. And what you build with it, should be simple enough you don't need any type system.

For people interested, there is a good episode on FullStackRadio on the topic http://www.fullstackradio.com/132