If I zoom out to see the whole contiguous 48 states, each pixel on my screen is about 10 square kilometers. Consider filling the screen with that 10 square kilometers. For say, San Francisco, that gives me 13000 people to place in something like a million pixels of white. That is a nice density for a dot map, but my screen is mostly white. If we want to keep the color density, when we zoom out to see the country, even San Francisco is going to be a mostly white pixel.

With continuous smooth zoom you could smoothly change the size of the person dot from a 1/10th of a pixel to one pixel and probably come up with a nice effect, but you'd need to be rendering at 30fps or so to be smooth and this web site doesn't seem to be built for that.