The reason Prohibition was repealed was not because "policy moved too fast." It was because Prohibition was a stupid idea and inevitably led to the rise of gangsters coining a fortune from bootlegging illegal liquor. Many policies have unforeseen (at least by politicians and ordinary people) consequences that are far worse than the ill they are supposed to address. The USA's inane "war on drugs" is another great example. In fact, the problem with thinking that the Overton Window is a guide to sensible policy is that most people are profoundly ignorant and have zero ability to imagine the consequences of anything, never mind complex social policy. Hence populist policies are always hugely harmful (did we really need Brexit and Trump to remind us? apparently so). The Overton Window is a useful metaphor but it is not in any way a means of establishing coherent and desirable public policies nor private attitudes. It is merely a measure of what the masses have been induced to believe is the current normal.