If youre activating Castle Garenbrig, this will be an 11/11 using that six mana
Again, this doesn't matter so much over the long term because the supply of these decks will be massive, so things will even out, but for the short term, having $30 more in value is a reason to take Stalwart Unity, Breeding Lethality, or Invent Superiority over the other two decks
This is especially true in decks that have other uses for creatures outside of attacking, like sacrificing them or tapping them for mana with abilities like convoke
These additions, as well as many others, have helped various fringe decks gain competitive footing
This makes Grim Backwoods particularly useful in decks that benefit from creature sacrifice mechanics, often seen in black and green decks where creatures can be reanimated or their death triggers are advantageous