Yes there is. It just ends with the loss of one stock, not the entire match. And even if it ends with the loss the entire stock, it does not prevent competition, it merely prevents that one character from being viable against D3.
In order to prevent Competition, it has to be something which, upon activation, ends the match right there and then, period. This includes freeze glitches, removing one or both opponents from the field and excessive stalling.
Of course, if D3's infinite actually shaved off all stocks at once, you could say that it ends the match right then, right there, but you see, in cases where it's a combo which prevents Competition and not merely a technique or glitch which freeze the game, remove one or both opponents from the field or just makes it impossible for you to hit them (invincibility glitches, excessive stalling), it is only ban-worthy for preventing competition if it is universal or at least near universal, thus over-centralizing the game.
Combos do not fall under "Prevents competition" because they are just that, combos.