This. And to have a variety of skills (mostly CHA, WIS, DEX, STR) covered for closing locations.
<3 Meri, Kyra, Seoni, Amiri. From a powergaming perspective, I would toss in Lini instead of Kyra, but I spent to much time with her that I can live with her shortcomings (which is mainly her lousy base STR die).
But as Hannibal said, many 3-4 player combos will work just fine. And it's not only the party setup, it's the player's experience (I still learn new things every day) and 20% of luck that turns games.