They aren't a doomsday group because they've made up a definition of one that they don't match but others who had "wrong expectations" are. But outside of the loaded language of Watchtower, in the everyday vernacular, they are.
With 1914, JWs are ignorant about the history of the teaching and its ultimate roots or their kinship to the Second Adventists and Millerites. Dozens of groups all predicted the end of a 2520 year period from years the 19th century to1917 to 1934. It just so happened that one of those groups predicted a year where something happened...just not anything they were predicting. Then after the fact they revised what the prediction was all about.