In other words, you’re pulling it out of your XXI-century anal orifice 
Futurism in Italy was characterised by heavy pro-war rhetoric, and it was enthusiastically embraced by fascist ideology later on. Not a surprise: these “artists” went as far as actually ambushing and beating a rival critic in large numbers, pioneering the sort of violent “many vs one” practice that will become typical of fascism. As others said, quite a few Italian futurists did enlist for WWI, and their main regret later on was that Italy had come out of that conflict with a diminished profile (we “won” only thanks to Allied pressure, barely scraping by, risking huge territorial losses at various points, and ending up with territorial gains everybody thought we did not deserve).
Obviously we are not going to judge the entire movement on a single element (futurism was hugely influential and evolved in forms that, in many ways, dominated XX century arts) and/or on a moral basis, but trying to say that futurists were joking when openly campaigning for war at every turn, is just preposterous, sorry.
