I mean, before the advent of GPS, ships at sea got a "fix" of their position by taking two measurements: north/south latitude (via a sextant when the sun was visible) and east/west longitude (via a set of very accurate clocks that showed the time in Greenwich England, which could be easily compared to the time aboard ship). Mercator maps are just a grid showing where all the land is as a function of these two measurements on the X and Y axes. Any other projection would have just meant a lot more work figuring out where shit was, which is why Mercator became "the" map. It had absolutely nothing to do with any attempt to make Europe appear dominant -- Europe's dominance when these maps came into existence was too obvious and unquestioned to need any parlor tricks.