I don't really see how this is different from "LLMs can't multiply 20 digit numbers"--which btw, most humans can't either. I tried it once (using pen and paper) and consistently made errors somewhere.
People made missiles and precise engineering like jet aircraft before we had computers, humans can do all of those things reliably just by spending more time thinking about it, inventing better strategies and using more paper.
Our brains weren't made to do such computations, but a general intelligence can solve the problem anyway by using what it has in a smart way.
But as long as AI cannot do that they cannot replace humans, and we are very far from that. Currently AI cannot even replace individual humans in most white collar jobs, and replacing entire team is way harder than replacing an individual, and then even harder is replacing workers in an entire field meaning the AI has to make research and advances on its own etc.
So like, we are still very far from AI completely being able to replace human thinking and thus be called AGI.
Or in other words, AI has to replace those giants to be able to replace humanity, since those giants are humans.