I've thought about this before, and the conclusion that I've come to are that dithering and anti-aliasing are both techniques from the wrong eras of pixel art.
Dithering is something that you need the most when you are working with either a very limited or a fixed color palette. On the NES backgrounds were dithered because you had so few colors to work with per tile. EGA era PC games used dithering because the standard 16 color choices weren't very useful. Modern pixel artist don't have these technical limitations to work with. And I think that for most, dithering just doesn't look very appealing vs adding an intermediate color.
Anti-aliasing is on the other side of technology window, from an era where there was enough resolution and color choices to support those techniques, but before 3d really took over. By the time you have that level of rendering capability, your are starting to push into the realm of photo-realistic or cartoon techniques. Late in the Super NES and VGA era the trend was away from hand drawn pixel art, and towards high resolution renders scaled down. And when you're working in that space today, you're starting to lose the appeal that the limitations of pixel art offer.
This is all conjecture though. And I'm sure there are pixel artists out there doing amazing things with dithering and anti-aliasing.
There's a lot of discussion about that in the "classic" pixel art circles. More generally, if you look at it from this angle, pixel art itself is "from the wrong era" of digital art since it is literally self-imposing constraints that maybe used to be there by external imposition but don't need to be anymore.
I've come to the conclusion that whatever we call "pixel art" is just a range of subjective preferences that may be more biased towards aesthetics, or techniques, or tradition, or even "pseudo-tradition". Nowadays the trend seems to be aesthetics with disregard to technique, but there are still many people who consider it "cheating" if you use the "wrong" tools, there are those who want to emulate the exact specs of certain machines, and there are those still who have a mashup of rules that aren't fully justified if not historically (the best example I know is Pixel Joint, but in the end their restrictions have created a community that has flourished and produced awesome art anyway).
To me it’s probably just the multiple meanings that are confusing.
Reading the replies in this thread I realize that to a lot of people it seems to mean a certain aesthetic (I.E. blocky pseudo-retro game graphics). Nothing wrong with that.
I guess I fall into the traditionalist camp. Pixel art to me is about working against fixed limitations to create an illusion of more colours, higher resolution etc.
Dithering is something that you need the most when you are working with either a very limited or a fixed color palette. On the NES backgrounds were dithered because you had so few colors to work with per tile. EGA era PC games used dithering because the standard 16 color choices weren't very useful. Modern pixel artist don't have these technical limitations to work with. And I think that for most, dithering just doesn't look very appealing vs adding an intermediate color.
Anti-aliasing is on the other side of technology window, from an era where there was enough resolution and color choices to support those techniques, but before 3d really took over. By the time you have that level of rendering capability, your are starting to push into the realm of photo-realistic or cartoon techniques. Late in the Super NES and VGA era the trend was away from hand drawn pixel art, and towards high resolution renders scaled down. And when you're working in that space today, you're starting to lose the appeal that the limitations of pixel art offer.
This is all conjecture though. And I'm sure there are pixel artists out there doing amazing things with dithering and anti-aliasing.