Having like, space, in your space game, is a pre-requisite for the genre.
Setting no man's skyn aside for a ment and just looking at this, it's not actually true. Neither Elite, Star Citizen or anything else I know of has a true contiguous universe. In SC I believe you'll have to warp from system to system, not sure what they plan if you try to fly. In Elite you can fly there but I think planets and things don't instance until you jump (do a 0AU jump). it basically comes down to the way computers store floating point numbers - not ALL real numbers can be represented and in fact as the numbers get bigger (or smaller too) the amount of error increases. So if you say the sun as 0,0,0 in the world, the further you get from the sun the greater the deviation between the number 'as it should be' and the closest representable number.
So changing star box via jumping or other means resets 0,0,0 to a new local coordinate to provide the best amount of "accurate" space, and distance spots (eg where you just jumped from) go from being accurate positions to approximations. It's an interesting problem and I know people are trying to come up with better solutions like shifting the origin (the 0 point) during regular flight but it's not as simple as that sounds.
So basically, floating point and fixed point fractional number representations in computer memory are not at all conducive to accurate position information over very large spaces and there's jack all you can do but code around it where you can.