I doubt that anyone would argue with that, but there is an issue of degree. Kobo readers have paragraph bugs that can leave a huge chunk of the screen blank. By that I mean there is several centimetres more blanks space than there should be for widows and orphans. I can see that as being a little bit distracting, since it can interfere with the flow of reading. Fretting about the footer and 1 to 2 cm variation on top of that seems a bit excessive though.