I've been writing operational apps with Svelte for over two years. I develop geospatial applications that make heavy use of WebGL. Haven't yet ran into any serious limitations. I keep things fairly simple and have been using tailwind the entire time. We had to fork a geospatial map framework (Cesium) to allow it to be loaded with Rollup.js as a simple javascript es6 module. But I wouldn't blame that on Svelte.