It does negate your "premise" completely. You simply don't understand why.
Show me an image taken from the highest optical observatory on earth - https://en.wikipedia.org/wiki/University_of_Tokyo_Atacama_Observatory
If the earth is flat, this observatory would be able to return an unobstructed view west across the Pacific to Australia, north to the Chicago skyline or east to Madagascar (because it is powerful enough to do so). And yet, it is unable to do so. Do you know why it is unable to do so? (It's because the earth is a sphere)
No, it is because the air is a medium and it eventually obscures the visual plane. I posted a video about the density of the air and how this effects our visual perception, you should check it out.