Personally I had some great and memorable experiences of collaboration in online multiplayer, and some forgettable experiences of just seeing the other players pass by and being meh about it like if they weren’t there.
I definitely do not think the online multiplayer is a factor on the game success, I don’t think it affected the game success at all. Just being a refreshing 2d Mario game, and the Mario Movie is enough.
I am not sure if the original quote of Shontaru Furukawa means online multiplayer or local multiplayer. The wording and context make me think of local multiplayer (“people can enjoy with family and friends during the year-end holiday season, when people get together”), but the half of the people playing multiplayer make me think of online multiplayer. The context of the interview (a Q&A by the end of fiscal year, for investors) make me think Furukawa is being vague on this on purpose.
It was pretty successful while it lasted, it always had a sunset date :(