our average NEW player isn't going to check out the market with their handful of credits because they won't know what to buy.

I beg to differ. Why would a new player not check out cheap cards on the market?

there is no concept of a "deck" in this game

Yes there is, each Splinter works as a separate deck of cards, except Dragon which has the ability to merge with another deck.

I understand that this decision is frustrating but I feel like this is better in the long run. The last players you want to alienate are those who have actually invested a lot of money in the game. But I understand that this comes at a price and that some feel frustrated by the move. However, the ability to play with cards that you do not own takes care of making sure new players can have fun and earn.