Eventually, they'll run out of Lands because they have to sac one when it enters, but this card is often played in decks running multiple Land drops a turn
Hour of Devastation included new creatures with Exert, and while some of them followed the same attack trigger formula, the bonuses they received were smaller, like Khenra Scrapper: +2/+0 until end of turn. Additionally, a small number of creatures could exert as an additional cost of an activated ability, like Hope Tender: Untap two target lands. Hope Tender could provide extra mana, but only every other turn
Unnatural Growth Its a house in Limited, Unnatural Growth looks to be excellent for Green-heavy Commander lists that care about being aggressive
Not only will it keep all of your creatures in play, it's going to allow you to draw a card for each creature a target opponent controls that is destroyed as a result of this spell
For just 2 mana, it does a ton of work and quickly becomes a must-answer threat