Yeah, I think it's more about what you are used to. I use the racing line to position myself correctly on the track, but similarly I could use either tire marks or signs or something else for that. The line is just easily detectable as green/yellow/red color stands out well from the grey surface. Of course the racing line can be used only for understanding your position on the track and not actual turning and braking points because the line is usually far from optimal. After practising a track for some time, the racing line becomes quite redundant, because you get used to the surroundings.