I think you may have missed the part where a LOD bypasses the internal amplifier section of the MP3 player. Internal amplifier sections are pretty underpowered for driving higher impedance headphones and using a LOD and external amplifier allows higher power. This also might have the side effect of increasing battery life.
If you are using stock Apple ear buds to listen to an iDevice, then LOD and external amplification is probably not worthwhile. I do know that driving Sennheiser HD280 Pros directly with my iPad, I can barely get sufficient volume before clipping like crazy. Using an LOD and a self-built Mini^3, I get good solid clear sound with adequate volume and no clipping beyond what the engineer introduced into the original recording. <grin>
Anyway, a LOD by itself is not just cable magic, it does serve a real technical purpose. As to effect of various wires, connectors, lengths, processes involved in making LODs, well, to each their own...