The difference between getting a bunch of stacks on Bonewall and getting a bunch of stacks on this card is that you need a kill-card for Bonewall. For example, in SG's Rainbow you would use an expensive Rain of Fire (with some Otyughs and Fallen Elves for support) and hope the enemy has enough enemy creatures with less than 4 health. In other decks, you may generate a bunch of Malignant Cells on your side of the field, or perhaps the enemy side, and use something like Dessication. This card, on the other hand, doesn't require that extra card, and isn't depending on killing your enemy creatures or your own creatures. In other words, at least in decks made for generating a high number of stacks, this card is more reliable and less self-crippling.
Just some thoughts. Compare it to Dimensional Shield when it replaces the Adrenalines in Mono-Life.