You, and everyone else who makes this argument seems to blatantly dismiss the tooling around Android, specifically Android Studio and the layout preview panel. The person you are responding to is talking about editing UI layouts in XML, using the preview panel, without building the project at all.

Everyone loves to talk about "hot reloading" and obsess over reducing build times incrementally as if that's the only way to develop anything faster. No matter how fast your "hot reload" is, it'll never beat the layout preview panel in Android Studio, which is directly rendering your xml in real time, without compiling or building anything.