The sneaker and sportswear giant may never be able to fully repair the damage it did to its competitive moat.Although I typically avoid stocks in the highly competitive apparel business, I once had a more favorable view of Nike (NKE -0.39%). It developed a reputation for producing high-quality products. Also, its brands backed by celebrities such as Michael Jordan and Cristiano Ronaldo drove massive sales increases over time.Unfortunately for Nike, it made one critical misstep that caused its sales to level ...