"We did a bunch of invites over the weekend and there was some wonkiness on how the messaging went out with lots of confusion which resulted in more silliness. We decided to just open it up. There will be an announcement about it on Steam soon."
Wonkiness leads to confusion; confusion leads to silliness; silliness is the path to a speedy Steam release. So, surprise! Go play some Super Monday Night Combat, because you totally can.