The cake binges and parties and pranks are based on the fact that outside of exposition all we ever really see her do is eat cake, go to parties, pull dumbass pranks, and then get Twilight to clean up after her mistakes.
That said, Jerry's full of shit. The basis for Tyrantlestia could have grounding in her negligent methods of ruling, apparently preferring to be hedonistic and at all other times be little more than a figurehead. Though really when you phrase it like that Molestia is more in line with the princess. A kind and patient benevolent dictator who constantly fails to prepare for threats, even ones she to a degree saw coming, not maintaining a real military force in a world where monsters do exist, not killing Discord, banishing her sister, letting a holiday depicting her sister as a cannibal like some kind of pony Dick Cheney, and again, entrusting her countries only obvious weapons to unstable teenagers, some of them incapable of forming close bonds? Say what you will about Hitler, he at least saw talent in Rommel who could have completely decimated the US front in Northern Africa if Hitler didn't go even more off the rails during the final months of the European front in World War 2.
And speaking of Hitler, his reference to Naziism was a bad one. Hitler got his seat through a manipulated election, he was an example of what happens when the safeguards of democracy fail. And are we sure America has a thing against dictators and forms of government not our own? We don't seem to have a problem with the practical military dictatorship in Israel which is a tyranny in itself with the way it handles Gaza and Palestine, and it acts surprised when the desperate civilians of the ethnic groups they abuse turn into terrorists, we haven't had a problem with the brutal theocratic state in Saudi Arabia, we backed several horrible South American dictators like Fulgenico Batista, we let our own corporations become practical dictatorships, and don't get me started on the South American death squads that swiss cheese brain Reagan backed. America doesn't have a problems with crowns and dictators, it has a problem with greedy idiots and a media so caught up in a bullshit ratings race most of it's people don't even know what's happening in it's own borders.