Margaret Hamilton, NASA's lead developer for Apollo program, stands next to all the code she wrote by hand that took humanity to the moon in 1969
We don't have a villainous empire like the soviets to beat there to prove we're better on the world stage. There was a lot of hand work and individual skill/knowledge that designed the rocket nozzles and those people either wrote it in notebooks or didn't write it at all so it was lost. That's what they mean when they say we lost the technology. Try asking your great grandparents for specific details about the career they had 50 years ago and see how far you get.