system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: NASA announced Juno's arrival as the hardest thing they've ever done...

yet they also put men on the moon using less computing power than you can find in a modern calculator.  Not to mention multiple previous exploratory missions to Jupiter. So what is it about Juno's mission that makes it the hardest?
Edit: let me clarify, I'm not asking because I doubt the claims, but because I'd like to know the technical reasons for the difficulty if anyone knows them.
gpt
Used a relatively small launch rocket so less fuel and mass to work with.

No Fuel for a nuclear RTG forced Juno to have the largest Solar panel area of any deep-space probe ever launched

Using only a single Earth gravity slingshot to Jupiter requiring more fuel than past missions. Other probes used Venus, Earth, Earth slingshots

They wanted it to orbit close to Jupiter so it had to survive the intense radiation without frying all the electronics.