alt Hacker NewsI think we can look to the SLS [1] for the answer there. It was basically NASA's answer to (amongst other things) get to the Moon in a kind-of-new way. For some historical context we first man a man in orbit in early 1962, so that was just barely starting to appreciate the systems involved in space. Kennedy would give his 'To the Moon' speech in late 1962. We'd then land a man on the Moon less than 7 years later.
The SLS started in 2011. 15 years later, it finally managed a manned flyby. The entire program has generally been an endless series of errors and mishaps, and the Moon flyby probably should never have happened, but was greenlit for political/managerial reasons - highly reminiscent of Columbia and Challenger, but with a better outcome owing purely to good fortune.
Not only has it been an endless series of mishaps over an increasingly absurd timeframe, but the program has already been obsoleted by the Falcon Heavy, to say nothing of the ongoing development of Starship. It has a lift capacity of about 50% more than the Falcon Heavy, but one SLS launch costs as much as 40 Falcon Heavy launches, so it's existence just doesn't make any sense, at least not as a space launch system.
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It seems likely that NASA would have been much better advised to have simply revived the Space Shuttle or perhaps even further back rather than trying to do something from scratch, simply because when you do it from scratch you end up trying to iterate on top of something that you no longer necessarily have the expertise or human knowledge of how to create.
I think where intuition fails a lot of us (myself included) is that in the software world if you have the code/documentation for something then building it is trivial. But in the hardware world, even if you have all the instructions and knowledge, actually applying that know how to create a working project is still very far away, through certainly nowhere near as far away as if you have started from scratch.