Maybe they used that experience decide that it would be cheaper to just build a huge rocket? The ISS also had the benefit of the shuttle, while US flights to LEO were in turmoil when the SLS was funded. It also wasn’t clear in hindsight how completely and utterly inept Boeing was and how effective SpaceX was going to be.

It's grossly more expensive the way they are doing it. They were originally going to use smaller commercial launchers until Senator Shelby and others held a political knife to their throats.

SLS has absolutely no redeeming features. You're sunk deep in Stockholm Syndrome if you're still defending it.

It's ironic that Musks two big successes were funded by the Obama administration against vehement Republican objections. Shelby repeatedly tried to kill Space-X and without the $400million DOE loan Tesla would never have been able to start production - and without the electric car tax credit - it never would have been able to sell.