The store page is kinda confusing. I don’t think the line “Join forces with other players to take on the creeping night and the dangers within featuring 3-player co-op.” along with both singleplayer and co-op listed as valid playing styles is something most reasonable people would interpret the way that it really is: be exactly 3 players with external voice chat available because all other ways of playing the game will suck hard.

They’ve been sorta honest about that in interviews and such but those don’t have the same reach as their huge marketing campaign.