Believe Hindenburg, Germany’s President, was dead, not in exile, when Hitler appointed himself President. The U.S. system requires the Presidential winner to become President, regardless as to the amount of votes, as long as that person has the majority of the Electoral Votes needed to become president. If that fails, as happened in 1824, the House of Representatives chooses the president.

Parliamentary systems may have a broader base, but the Constitution specifically prevents the Vice-President upon becoming president to do much in the way of enforcing their views, without the consent of Congress, and then review of the Courts.

Germany trusted Hindenburg, much like early America trusted Washington. The presidency was created based on Washington. The trouble was that America had the advantage of English history, Parliament, and democracy as ideals, Germany did not. Safeguards were not put into the system, in Germany, so when someone like Hitler came along, totally unprincipled, there were no circuit breaker to stop him from achieving his aims.