They basically enable the affinity archetypes in the format, which makes it easier to drop Myr Enforcers and Frogmites left and right
Getting to double dip thanks to persist makes this both resilient and impactful, plus it enables infinite loops that destroy all your opponents lands
With this in mind, cards like Evolution Sage and Contentious Plan can still be effective through card draws even if they don't provide immediate value
It can kill planswalkers, block effectively or put people into range of being one shot by a lot of your big cards
[1] Lorcana usually works best as a 2-player game, but you can play as many people as you want
This means deckbuilding is a matter of dividing all of your bombs up, but even in a high power format like Dominaria, its rare that youll be able to field three powerful decks