restricted to only 3 companions is very punishing for a story based game.
Someone needs to play Disco Elysium. The story was great and you only had 2 characters to play with. Trying to argue the benefits of a harem over monogamy is just silly. Just because a story isn't a six way gangbang doesn't mean it's less of a story.
Can we also drop the "just play with less characters" argument while we're at it? You're literally saying, "that's just your opinion man". You've given up the argument at that point - if you're going you're own way then you're throwing yourself off of the ship. You're not steering it.
I mean, with the fact that DOS had slower gameplay because you had a fatter "action economy wallet", I get what 6-party stans are on about. The pace of play with 4 characters is weirdly quick. D&D5 is designed to get turns done quickly.
That's why bonus actions have been abused by the designers - to give characters something to do on their turn.