@JimmyT - I understand where you are going and that getting an ammendment passed based on your party's platform is a phenomenal achievement, but nothing comes close to having one of your own elected President.
Prohibition was the main part of the Prohibition Party's platform, but there were other policies that they wanted to institute as the policies of the United States. Had they had one of their own elected, they would in essence have been in charge of one branch of government, the Executive Branch.
Since the President can appoint people to federal jobs, the Prohibition Party President could have appointed so many Prohibition Party members to various government jobs, putting the party's stamp on various institutions, especially the Judicial Branch and federally elected judges.
One cannot take for granted the power that the President has and this is the ultimate goal of any party due to the power the President has and the impact that their appointments could have for decades to come.