While indeed, to land a hit, you must first convince your opponent that there's no way to avoid it, the combined information provided by character sheets and combat posts creates an objective frame of reference, meaning that with cunning enough manipulation of the fight's flow, one can create a situation where their opponent can no longer deny that they're in a disadvantageous position and have no means of escape.

Of course, the abscence of a rigid system present in most games dictates a reliance on sportsmanship and trust - but third party review, presented by the tournament's appointed judges, can provide a higher degree of reliability, satisfactory to all but the rarest of cases.

In short, yes, you have to be stubborn and thick skinned to a degree - but those qualities by themselves don't decide the victor.