> I have no clue why anyone would choose to write a single line of JavaScript in this day and age, but each to their own.

You should already have a clue, you have to write a lot of JavaScript in order to get Svelte doing what you'd expect outside of very simple components. See these actions as an example, and check out the JS file! https://svelte.dev/tutorial/svelte/actions

Svelte makes more sense if you enjoy the JavaScriptisms. In which it provides enough "magic" for most things, but still lets you enjoy JavaScript.