To be a competent engineer in 2010s, all you really had to do was understand fundamental and be good enough at google searching to find out what the problem is, either for stack overflow posts, github code examples, or documentation.
Now, you still have to be competent enough to formulate the right questions, but the LLMs do all the other stuff for you including copy and paste.
But given a sufficiently hard task for which the data is not in the training set in explicit format, its pretty easy to see how LLMs can't reason.