Why is a group of four players the standard for the majority of games?

Question

Be it TTRPGs, board games or video games, a group of four players is the standard size.

DnD and adjacent systems balance their challenges around a party of four. Most boardgames come with four colours for players to choose from. Most video game consoles only can connect four controllers and most video games like Smash Bros and Mario Kart only have four slots? Why is that?

In: Other

Answer 1

In TTRPGs, the simple answer is that every player adds more overhead, more time that the other players are potentially waiting for the GM to get around to them during a particular scene or combat round. In roleplay-heavy games, it means there are more character backstories to consider and accommodate, which is more work for the GM.