I don't know where you get "less functionality and worse performance in the same or half as much space"- the point of the link was to show that 256 byte demos actually demonstrate more functionality. What makes you think you have more functionality in 1k of JS?
As you said, "if you could get the WebGL syntax overhead to work in 1k, you could kick the crap out of the 256 byte demos." I believe that's exactly the point. Even if there is all this theoretical power in our JS environments, we aren't using our environment nearly as efficiently as the 256 byte demos used theirs.
It's also worth noting that those 256b demos ran on the standard platforms of their day, which yes, required MS-DOS, but then could run on any intel compatible processor, with any standard motherboard, with any standard bios, with any standard video card. And I would be surprised if they actually called into MS-DOS at all, and didn't just talk to the hardware directly.
As you said, "if you could get the WebGL syntax overhead to work in 1k, you could kick the crap out of the 256 byte demos." I believe that's exactly the point. Even if there is all this theoretical power in our JS environments, we aren't using our environment nearly as efficiently as the 256 byte demos used theirs.
It's also worth noting that those 256b demos ran on the standard platforms of their day, which yes, required MS-DOS, but then could run on any intel compatible processor, with any standard motherboard, with any standard bios, with any standard video card. And I would be surprised if they actually called into MS-DOS at all, and didn't just talk to the hardware directly.