Noise reads like, well, noise. It makes things unclear in a medium where clarity is already a challenge. It's best to avoid it. In addition, using a filter (as opposed to just noisy pixelling) adds a lot of colours without your direct control, which makes colour management and tweaking a big pain. Pixel art tutorials don't usually mention noise for the same reason painting tutorials don't mention chisels - it's just not usually a useful tool for the medium.