It's GG because you follow it up with other spells that they can't deal with without mana. Also, it's very rare that they'd be able to put all 4 basics out and many lists only play 2-3; at 2-3 they can effectively play one spell a turn and if there's a Propaganda out, they can either play a spell or attack once per turn. At that point it just takes a 'Pling, Shackles, Keg or a second Propaganda to end it.