The problem with dithering is that pixels are shaking, it's worst when reading texts, as eyes are trying to focus on something that is shaking, a sense of strain and headache will be formed. Some people will be more susceptible to the shaking pixels while others wont be as much. Watching videos will cause less stress on eyes then reading text.
As soon as I disabled the intel graphic, I could notice that pixels became static, and the strain immediately gone. It feels like reading on paper.