Yep, that is what happened. Kerberos and Paradox knew the game was not finished, which is why they delayed the retail release. However, Kerberos was out of funds and Paradox wasn't going to give them any more money so the game was released digitally so they could use the digital sales for further funding to finish the game.
There is supposed to be another patch coming out tomorrow.
most people have paid for the alpha/beta versions of minecraft, or some other alpha game. This is more or less the same thing, youve helped keep their development going. If they hadnt gotten more money from us to fund the final delvelopment of the game, it could have been canceled all together. Many games have been almost completed but have run out of money, and then been canceled