Ummm I don't think ANYONE here questions the fact that higher resolution provides more detail and clarity when rendering a document (PDF in your specific case). The only concern is applying the high resolution display to a such small physical screen area that it's not practical anymore. That the benefit is lost due to other bottlenecks (your frickin eyes) meanwhile it puts unnecessary burden to the system, cost and whatever else.
Please reread all the previous posts with this fact in mind and I think we'll be on the same page.