There is an English idiom — "It's not rocket science" — which roughly means something isn't that difficult. For instance, putting an elephant in a refrigerator isn't rocket science, because it's simple: open the fridge door, put the elephant in (and remember to close the door again). The vast majority of things we encounter in life and work fall into the category of putting-an-elephant-in-a-refrigerator. To say something "isn't rocket science" means it's not beyond our comprehension — as long as you have basic knowledge and follow a reasonable method, you can get it done.
One implication of this idiom is: things aren't that hard. Don't assume they're that hard. Don't mystify them (the way rocket science seems mystifying). Putting an elephant in a refrigerator — there's nothing about it that defies ordinary understanding.
But on the other hand, putting an elephant in a refrigerator isn't necessarily that easy either. There are many specifics involved, which is obvious. If someone takes on this task, finds a refrigerator, opens the door and tries to shove the elephant in — that's clearly not going to work, right? With an ordinary elephant and an ordinary refrigerator, you can't do it without cutting the elephant up. "Cutting up" — or rather "killing open" — is a term invented by Xiao Yuan (Ma Xiaoyuan), referring to the act of using blades to split something apart. To fit an elephant in a small fridge, you have to "kill it open" and chop it into pieces small enough to fit. This requires determining the cutting method based on the elephant's anatomy, as well as obtaining an elephant slaughtering permit. Some people who've done the putting-a-cow-in-a-fridge job will helpfully instruct you: for this kind of thing, you need to find an imam to recite prayers, otherwise you're not progressive. They see you fussing with the elephant's trunk and laugh at you — just put the whole head in the fridge, that's standard industry practice, this isn't rocket science, why are you messing with the trunk? Isn't that ridiculous?
The point here is that putting an elephant in a refrigerator, while not rocket science, still has its own principles and its own specific problems to address. To do it well, we still need first-principles thinking. You can't just take your experience watching Master Pao butcher a cow and start pontificating about Zhao Benshan putting an elephant in a fridge, spouting all manner of nonsense.
Furthermore, problems can sometimes be solved in unconventional ways by reframing the constraints. A refrigerator factory, for instance, would simply build a giant refrigerator — then its challenge becomes designing a space within the large fridge suited for elephant storage, rather than butchering the elephant. Some people, disciples of Master Pao, see the factory people and say they don't understand slaughter. "This isn't rocket science," they say. "Why build such a huge fridge? You should buy one from JD.com. I hear Haier's are good. Let me tell you how to set the temperature controls." This is dogmatism. There's a great deal of dogmatism in this world. Far too much.
Finally, when this idiom was coined, Elon Musk hadn't yet gotten into rocket science. After Musk did get into rocket science, rocket science itself stopped being rocket science — everyone saw a bunch of people welding in the open air, clearly employing physical principles we can all understand to send rockets into space, and we realized that rocket science isn't rocket science either. Which is to say: first, nothing in this world is truly "rocket science" — wherever physical laws apply, physical laws apply, and we can solve all problems using methods that ordinary people can understand (of course, some specialized knowledge is required, but there's nothing mystical about any of it); second, everything has its complexity, and the reason it isn't "rocket science" is precisely because we refuse to mystify it — we approach specific problems concretely, in a spirit of seeking truth from facts, breaking free of dogmatism. Only then can the elephant situation be handled properly.