The following is solely my opinion. Though play testing a lot, this is my surmizal of the Primal faction.
First the benefits of Primal. It's got card draw. It's got transformation effect. It's got copy unit effects.
What the faction is severely lacking. Independent Lifegain, and weak armor generation. Severely under statted units across the board. For example it's got fliers. Justice has tougher fliers. It's got dinosaurs for the ground assault. Time has tougher dinosaurs and sentinels. It just always seems to be playing catch up to other factions in most criteria. It's power Standard is ultra trash.
So to make the faction competitive. It needs other factions' help. For an aggro build it needs Fire. For a brutal ground assault it needs Time. For life and armor boosts it needs Justice. For void draw, it needs Shadow. It's just weak sauce on white bread.
So in a budget Even deck. The only independently beneficial cards you can fit with most factions are.
Master Cartographer. Strategize. Mass entomacy. And last Sudden schism. That's it, out of five sets. I'm not counting the Campaigns.
Now a good percentage of daily quests, require. Draw x extra cards, play x amount of fliers, play x Primal influence, deal x damage with Primal. So you have to include in your brewing.
Also when I'm spending shiftstone on rares. Primal seems to almost always fall to the back of the line. Other factions can just achieve what I want more efficiently. Again this is just my opinion. Stay cheapskates friends. 👍