While it is true that the instant is punishing to decks like Merfolk and that the combination of Punishing Fire and Grove of the Burnwillows is a strong engine if the game goes extremely long, if you look back at the Modern format from Worlds 2011 (the tournament cited in the banned announcement), it looked a lot different than Modern does today
After the loss of Castle Fynn, the survivors flee to nearby Altair, where the rebellion makes a temporary headquarters
Certianly the spot removal aspect of this hits a wider range of dorks than Shreikmaw but you can't do it for two
Naturally, players can build on and modify the Starter Decks as they collect more cards, or use their new knowledge to make a new deck from scratch using some of the cards in the Starter Decks
The extent to which these were printed is dubious, although I recall hearing the print run was less than one out of every 1,000 packs