IMO Shadertoy is not a good place to start. The techniques shown on shadertoy are fun to play with but they have almost nothing to do with the techniques used to make shipping products. Drawing an entire forest in a single shader is amazing but it runs at 0.2fps on a machine that can run GTA5 at 30-60fps
I would agree - Shadertoy is really cool, but it fits into the category of "they did it because they could, not because they should." There are techniques used in Shadertoys that are relevant elsewhere, though the learning curve is really steep in terms of comprehending what most Shadertoys are doing.
