Even more than the difficulty or amount of game mechanics, the reason why games like Rimworld, Zomboid or Factorio are the bane of Phail's existence is because there's no real goals at the end of the day. Sure, Rimworld iirc has the objective of escaping the planet or some shit but most people I know don't even give a shit about that objective, they just have their own goal in mind and try to achieve it. Hell, we've seen from his Minecraft streams, unless the dents tell him what the fuck to do or build his empty head can't think of anything to do.
I personally like Kenshi and it's the same thing, with most people either deciding on running an adventuring band or even a single character, or they decide on base building. I think it's easier than some of the other similar games because it's more difficult to completely lose, you can easily suffer catastrophic setbacks, sure, but unless your character/entire party gets knocked out by characters that don't give a shit about murking them (fogmen, skin bandits, cannibal tribes, beak things and spiders) the worst that can really happen is that the Holy Nation enslaves you, while the most likely actual outcome is that your dudes are gonna get looted. Not to mention, even getting knocked the fuck out still makes you progress in Kenshi, as getting hit or knocked out raises toughness, and coming to while surrounded by enemies raises toughness by a lot.