Fridge Horror: The Repairer of Reputations's America may resemble the America of the late 2010s more than the 1920s.
Harsher in Hindsight: Where do we begin? The US entering and winning a war with Germany?A seemingly opulent but corrupt decade following in its wake?Russia being taken over by radicalswho eventually conquer much of Eastern Europe?A superficially benevolent but totalitarian government creating death chambers? When the book came out, a major war with Germany was increasingly obviously coming; there were a few instances where said war almost happened a decade earlier than it did. Also increasingly obvious was the power of the USA in the coming century; by 1900, the US was already the top industrial power in the world. That Russia would be a superpower as well was also already predicted in the 1890s.note One of the biggest reasons for Germany's bad attitude in 1914 was a general feeling among Germany's political and military leaders that a war with Russia was A) inevitable and B) had to be completed by 1917-1919 before Russia developed too much for Germany to have a chance. There was also a strong feeling by Europeans that, in spite of the USA's 19th century track record on these things, the US would play a major part in said war.note While Americans liked to attribute their tendency towards isolationism to George Washington's farewell speech, the truth was that the 19thC United States's isolationism was mainly caused by their obsession with settling their entire continent. At the time that The King in Yellow was released, this had just finished. Not coincidentally, the Spanish-American War was started by the Americans a few years later.
Values Dissonance: The American reforms apparently include banning "foreign-born Jews," among other questionable things, and are claimed to have ushered in an era of "tolerance and equality."
Of course this is according to the narrator of the story, who's also a blackmailer and batshit crazy. So you don't necessarily have to take the sentiment at face value.
The narrator of The Repairer of Reputations mentions that he has been unable to work, and in fact has been a social recluse, since being thrown from a horse a few years prior. His cousin Louis appears to be his only mentally stable social contact and possibly responsible for his material support as well. The things the narrator describes may very well be distortions of reality ("suicide chambers" are subway entrances; the military parade is actually a regular police patrol; the battleships are regular merchant vessels). Louis remarks that the crown the narrator removes from a safe is actually a theater prop he was keeping in a biscuit tin. This all sounds like the result of the traumatic brain injury the narrator suffered in his riding accident.
Vindicated by History: To an extent—Robert Chambers actually wrote very little weird fiction, and even in this book, certain stories tie in to his other (non-horror) works. In his lifetime, Chambers was a hugely successful writer of historical fiction and romance. In modern times, The King in Yellow is possibly his most well-known work, considering its references in the Cthulhu Mythos and True Detective, while his other works are less-remembered.
At various points the play indulges in ham-fisted political commentary about civil liberties and indefinite detention and various other comments that the reader might assume are obvious references to post-9/11 America. Until you remember that the book was written in 1999!
Several dominant political and ideological tendencies in the US after 9/11 were already starting to appear by 1999.