Animal crossing came out at the same time lockdowns happened. It just happened to be the killer app people got with the Switch due to Covid.
It would have been a huge killer app with or without covid. It broadened the system's appeal to a huge untapped audience and greatly increased Switch's appeal to women and casuals.
Bet with Liquidlaser: I say PS5 and Xbox Series will sell more than 56 million combined by the end of 2023. (And over 130 million lifetime)