alt Hacker NewsSerifs are chosen intentionally to be harmonious with the overall letterforms. They provide a feeling of visual stability and additional cues for recognizing letterforms. They provide a kind of consistency. They're not a distraction.
Jaggies come from a limitation of the pixel grid. They arbitrarily make diagonal strokes and curves bumpy while horizontal and vertical strokes are perfectly smooth, an inconsistency that would otherwise have no rhyme or reason behind it. Before letterforms were constrained to square grids, nobody was making diagonals and curves bumpy because it was a desirable aesthetic effect.
Jaggies are a distraction from the underlying letterform we all recognize. We know they are an undesirable distortion. Serifs are not. They serve an intentional aesthetic purpose, proportioned in a carefully balanced way.
Serifs are a skeuomorphic artifact of stone-carved text. They're no more legible than sans-serif fonts (see https://news.ycombinator.com/item?id=47492894 ). The only reason people like them is because they're used to them. You can get the same feeling from bitmap fonts if you read them enough.