This is one of the things where people are "split on what a space sim actually involves", certainly.What game besides Elite has a more or less real universe ? Well, not about the name of the systems, but the distance between bodies in the systems, the rotation of these bodies, gravity, etc. ?
The basics of distance + rotation + gravity aren't all that difficult in themselves - FE2 did that back in the 90s, for example - but in most games set in space implementing them would get in the way of the desired gameplay rather than add to it.
Kerbal Space Program is the other modern example with realistic distances, sizes, orbits, rotations, gravity, etc. ... and also realistic thruster capabilities and travel speeds, which Elite Dangerous avoids implementing because it wouldn't work for the sort of game Frontier wanted to make.