They'd be gaining massive card advantage, but what use is it your opponent is down four lands, he's out of cards, and you are dead
Of course, seeing as this card is designed for Commander play and seeing how power creep has impacted Magic over the years, this card is rather pushed for Goblin players
If anything, adding MDFCs has added a whole new axis of deck-building and increased the range and complexity of decision-making around land drops to a level usually only seen in formats with Wasteland and Brainstorm
For a Shadow the Hedgehog Commander deck, you'll be playing a ton of cards with haste as Shadow's effect plays with that alongside having a sub-Treasure theme to make all your spells unable to be interacted with
It also does work in the occasional Mill deck
If you were on the fence about trying him out, now is the time