Svelte does two things very well: it's easy to integrate with other vanilla and not js technologies and opens up the space of your solutions. You don't have to have full buy in in it. You are not forced to do things how the framework want you to think about them. That's alone is a big win against React in my book, where you are not doing web dev, you are doing React dev, and sometimes that is way too constrained. That's is also a reason why Svelte is not irrelevant. It doesn't need to become React to be useful.