When they started the project (2011) Starship wasn't even a twinkle in Elon's eye (BFR around 2016). Starship started looking like a real product in 2020. In

When they started the project (2011) Starship wasn't even a twinkle in Elon's eye (BFR around 2016). Starship started looking like a real product in 2020. In hindsight, you're right, SLS looks silly, but not many people were betting on SpaceX developing a super heavy launch system in 6 years like they've (apparently) done. They've invested a lot of money in SLS and there's probably still lessons to learn there. If Starship is successful SLS will probably not be deployed very frequently.