Just a guess, but you may have in mind certain PS files generated by TeX/LaTeX from the 80s and 90s, back in the day when both PS-based workflows and raster (bitmap) fonts were more common than they are today. So, although it's not really a limitation of PostScript, for purely historical reasons there may be a correlation among academic documents between PS files and raster fonts, which (because of a lack of hinting) look worse on the screen, at resolutions other than the one they were tuned for. For such documents (try this if you have one of them), there is the amazing pkfix tool by Heiko Oberdiek: I had once written a blog post about this (https://shreevatsa.wordpress.com/2011/05/05/converting-old-p...) but you can read the TeX FAQ (http://www.texfaq.org/FAQ-pkfix) or even Wikipedia (https://en.wikipedia.org/w/index.php?title=Pkfix&oldid=71250...) or see it in action in this answer by the author: https://tex.stackexchange.com/questions/120260/making-low-qu...
