I think the reason it was exercised was because Lucas actually was showing Luke's father as a boy in Episode I, obviously without any Rebel Leader character, so for the purposes of continuity he decided to make things easier and snip it out. Because honestly if he left it in we would all be here complaining about how in Star Wars red leader says he knew Anakin as a boy but in Episode I theres no mention of him. Theres enough continuity issues in the PT as it is, here was one that Lucas actually caught.