Now copy area of a big area 100 times. Now do it 100 more. Wait no, do it 85 times. And they need to have red and green wires connected between the copies. Then you tried copying moving trains and now your trains are broken.
Having a mod means I can most of the problems the normal clone has and make it fast and precise to do lots of copies, with some extra features.
This mod is only intended for scaling up designs to run benchmarks. A simple 1x clone is probably just as easy if not easier with the editor (provided you don't clone anything that the devs aren't willing to fix, like moving trains).