Assuming that you're talking about GCOL (which is the topic of this thread) the point is that the time may come when you have no choice. Currently OpenGL remains supported in Windows, MacOS, Linux, Android and iOS; whilst that remains the case the 'traditional' GCOL operations (OR, AND, XOR, NOT) will continue to work.
But Apple has already deprecated OpenGL in MacOS, and if history is any guide that probably means they will remove it (in favour of Metal) eventually. Similarly it's not impossible that OpenGL will be replaced by Vulkan in Linux, although I would not expect that to happen soon. So even if you choose to avoid the Emscripten / WebAssembly environment you may still have to embrace the revised GCOL specification eventually.
The in-browser edition allows you to test compatibility now, so you are prepared should this happen.