As zwift is still a game, it falls under the category of eSports.
It should be able to create a private race between a 2 (or more?) riders (H2H mode or something), in this way, tournaments can be created by eSport tournament organisations.
two ways this could work, a separate course for say a 1k match sprint or something or an impromptu race option where you challenge nearby riders to a sprint to a nearby landmark