Svelte was first released in 2016 and has become bigger than its original creator, Rich Harris. It has quite a thriving ecosystem and a big community. The tooling around it is more mature than React's has ever been.
> surface is so small
I actually find the opposite to be true. React still has a relatively small API surface area. One-way data flow makes it easier to understand. However, a smaller surface means arguably less expressivity, so I think Svelte's bigger learning curve is worth it. You can learn about 90% of React in a weekend and be productive. You can learn about 20% of Svelte in a weekend and also be somewhat productive, but you need to learn about 60-70% more to use Svelte as it's intended, rather than as a React alternative.