How is it imprecise? It's the same thing as taking two containers of water and pouring them into a third one. It will contain the sum of the precious two exactly. Or if you use gears to simulate orbits. Rounding errors are a digital thing.

Analog has its own set of issues (e.g. noise, losses, repeatability), but precision is not one of them. Arguably, the main reason digital took over is because it's programmable and it's good for general computing. Turing completeness means you can do anything if you throw enough memory and time at it, while analog circuits are purpose-made