I've heard people invoke "Poe's Law" plenty of times. The correct usage is in calling out someone who responds seriously to parody because they did not correctly see it as such. Used correctly, Poe's Law is an identity: It holds that without obvious tags, it is impossible to create a parody of extremism that will not be seen as true extremism by someone. Therefore, all parodies without disclaimers would be "Poes." The Venn Diagram of "Poes" and "parodies" would be one big magenta circle. Sorry if this comes across as beating you up. That's not my intent. It just gets my hackles up when I see a perfectly precise, correct word replaced by a clumsy and imprecise newcomer whose syntax and usage are radically worse than that which it replaces. "Parody" and "Satire" have etymologies and syntaxes that date back to Sophocles; "Poe's Law" goes back to the 2nd GWB administration and "pulling a Poe" hearkens clear back to 4chan. Sophocles wins.