I might agree that leaping in and of itself does not provide a competitive advantage. However, you need to look at it on a pitcher by pitcher basis. If when required to pitch legally a pitchers performance falls off, leaping for that specific pitcher is certainly a competitive advantage. That said I think that for the majority of skippys like Barnhill, Silkwood etc. it is definitely a competitive advantage. Were it not for the leap and subsequent replant and push I doubt they could last an inning.
Since it is possible for a pitcher to replant without leaping, my contention is that the replant, and subsequent repush, are more of an advantage than a leap.