Having worked with React for about 5 years (with a project in Vue in-between) and now having dabbled with Svelte, there is just something more appealing working with less higher-level abstractions. Sure with large apps React does have its benefits and its ecosystem is larger by a good amount.
But there is just something about being less annoying that to me is perhaps one of the most important things with any tool. If I enjoy using it, I don't mind that it may not be the "current best choice" of the moment. People who enjoy MobX especially I think ought to find Svelte quite nice.
Sure though would wish SvelteKit was at the same level with Next.js. Fixing dev server errors is a little distracting at times.