I was thinking of that due to a specific problem I have for my game night tonight: I don't know how many people will be there to play with me. Usually I try to organize that in advance on the Discord of my friendly local games store, but this time I got a cancellation and only one other player who said he wanted to play the game I proposed. That game is Aeterna, a midweight Euro game. 90% of players on BGG think that 4 players is the best player count, while 43% wouldn't want to play it with 2 players. So I decided to bring a backup: If I have 4 players, I'll play Aeterna. If I have only 2, I'll play Vantage, which is best with 2 or 3 players.

Aeterna is a game with some area control. Those games are very susceptible to player count. For example, I recently played Wroth with 3 players. But Wroth is a rather aggressive "take that" area control game, where you kill the units of the other players. 3 players wasn't much fun, because after pulling off a great move and pulling ahead, the two other players ganged up on me. Not much fun for me, although I eventually still won, but also not fun for them, as they had to concentrate on keeping me down, preventing them from doing their thing. Aeterna is less aggressive, but the area to fight over doesn't perfectly scale to player count, so it makes a big difference whether 4 players are fighting for 7 spots, or 3 players are fighting for 6 spots.

Vantage kind of has the opposite problem: There isn't much interaction between players. Every player experiences his own story, separate from the others. If you play that with 4 to 6 people, although technically possible, it just takes very long between your turns. And it is hard for everybody to remember the situations of all players. With 2 or 3 players, your turn comes around often enough, and you can still take an interest in what is happening to the others.