It has been over fifteen years since the above write-up, and jpeg artifacts are still with us. In fact, jpeg artifacts have increased in some places, and along with being a technical phenomena, as described above, they also have taken on a social meaning.
It is somewhat surprising that images with jpeg artifacts continue to be shared across the internet, given the technical improvements in both storage and bandwidth in the past decade and a half. In 2000, dial-up internet was still standard and hard drive sizes averaged a few gigs at most, so keeping images under 100k made sense. 100k equalled a 20 second download time at 5/k a second, and that meant a page with three images of that size on it would take a minute to load. Given those limitations, it makes sense to put up with a little blurring in our images. But now, when download times can be hundreds of times faster and hard drives a thousand times as spacious, why are heavily artifacted jpegs still floating around?
Like so much, social media, specifically Facebook, happened. Facebook's photo page autocompresses uploaded photos. With some pictures, such as pictures of people and landscapes, this doesn't matter, because the compression naturally blends colors. But with other pictures, especially with so-called "memes" that include writing, it is rather obvious. Captions on memes often have colored writing on a white background, something that is prime territory for artifacts. Artifacting has taken on a certain political and social meaning as well: there seems to be a link between the banality, triteness and simple-mindedness of a meme and the badness of the artifacting of the image.
Along with this, artifacting can also be used intentionally, as compressing images can sometimes give images a dreamy, unreal quality that has some artistic merit in it. Along with this "serious" artistic use, jpeg artifacts can also be used "ironically" as they were masterfully in the webcomic Sweet Bro And Hella Jeff.