Ethernet cables like all other interconnects in high end audio can make a significant difference, depending on your system and components they can make an almost imperceptible difference or a very substantial one. Matching the cost with the improvement by experimentation is a prudent method to choose cables. I use DHLabs and Cardas Ethernet cables although I have tried a few others,
Applying logic as to why they should or should not make a difference is best done after you have tried a variety of them,