Technically, it’s not just about the download pipe. A 2MB+ WASM blob or JS bundle imposes a heavy CPU parse/compile tax. On mid-tier mobile devices, this results in main-thread jank and a 'Time to Interactive' (TTI) that kills user retention before the first frame even renders.
Beyond that, the 'Canvas-only' approach is computationally expensive. You are effectively re-implementing a rendering engine (layout, hit-testing, paint) on top of a rendering engine. While the browser's native DOM/CSS engine is a highly optimized, hardware-accelerated C++ powerhouse, a Canvas-only app has to manually calculate every pixel and handle every event in the WASM/JS loop. This drains battery faster and runs hotter than letting the browser do what it was built for.
Beyond that, the 'Canvas-only' approach is computationally expensive. You are effectively re-implementing a rendering engine (layout, hit-testing, paint) on top of a rendering engine. While the browser's native DOM/CSS engine is a highly optimized, hardware-accelerated C++ powerhouse, a Canvas-only app has to manually calculate every pixel and handle every event in the WASM/JS loop. This drains battery faster and runs hotter than letting the browser do what it was built for.