This is absolutely incorrect. Posted wait times are based on multiple factors: data from the cards handed out in the queue, the current capacity of the attraction, and the Cast Members' history/knowledge of the queue. Then, the posting is dependent on having someone available to update the time. Even then, all of this is based on either what the wait is estimated currently, or what it is reported as over the previous 1-2 hours. Due to all of these factors, plus good ol' fashioned human error, the posted wait time is always an estimate, but one that Cast Members hope is fairly accurate. At no time are wait times encouraged to be artificially inflated.
Source: Me, I am one of the people who updates the wait times.