Is everyone new? New players don't really know what they are doing to put it plainly. I can't even imagine what kind of board state there is if no one is buying riverboats or mercs for 1 and cards for 1 and 2. I have played a lot, dozens and dozens of games, and the Riverfolk have no trouble winning.
Cats vs Lizards vs Vagabond vs Riverfolk
I guess most people were new-ish. Cats were going for Domination at the end and fighting off Lizards who spread everywhere and the Vagabond was getting (and won with) Alliance points with the Cats. My Riverfolk could only get up to 24 points. When I got nearish to 20, no one wanted to give me warriors. A few cards in the beginning were bought at one or two but towards end game, no one was really buying anything unless it was an Ambush. Someone would be about to buy riverboat but realized they didn't need it.