That is stylistically how samurai clashes go in movies... Going past each other and sheathing dramatically.
Is Oda supposed to not have that symbolism because it gives you an unrealistic idea of the speeds involved, should he avoid showing you Luffy's punches because you don't have observation haki and superspeed reactions to see it? Wtf...
Soru itself made people disappear until they got accustomed to it.
Gatling alone (base form, long long ago) moves faster than the eye can see making it look like his fists are multiplying from speed alone.
Jet gattling made Luffy's fists disappear entirely when it was originally used as he was attacking, this wasn't a stylistic single clash, but his fists getting even faster and faster in an already vastly boosted MODE.