I've played around with doing some computation in WebGL, but it was rather tedious and difficult with my limited knowledge about the topic. It's possible, but you can't even rely on floating point texture to be available on all systems, especially mobile. And for anything more complicated, you probably need to be able to render to floating point textures, which is even more rare than support for plain floating point textures.

This only makes it more impressive when people do cool computational stuff in WebGL, but I'd wish there were some easier ways for non-experts in shader programming to do some calculations in WebGL.