You're missing the point.

WebGL runs everywhere that is objectively a Good Thing™. Your criticism is aimed at the optimisation rather than the technology.

The person who created this could, theoretically, add a little slider to let you adjust the visual quality to meet your PC's performance characteristics.

Additionally WebGL can also be utilised for things which only get rendered once (e.g. single 3D frames). Like generating 3D graphs for one suitable example.