If you can reduce a problem to a point where it can be solved by simple code you can get the rest of the solution very quickly.
Reducing a problem to a point where it can be solved with simple code takes a lot of skill and experience and is generally still quite a time-consuming process.
Isn't the logical endpoint of this equivalent to printing out a Stackoverflow answer and manually typing it into your computer instead of copy-and-pasting?
Nitpicks aside, I agree that contemporary AIs can be great for quickly getting up to speed with a code base. Both a new library or language you want to be using, and your own organisation's legacy code.
One of the biggest advantages of using established ecosystem was that stack-overflow had a robust repository of already answered questions (and you could also buy books on it). With AI you can immediately cook up your own Stackoverflow community equivalent that provides answers promptly instead of closing your question as off-topic.
And I pick Stackoverflow deliberately: it's a great resources, but not reliable enough to use blindly. I feel we are in a similar situation with AI at the moment. This will change gradually as the models become better. Just like Stackoverflow required less expertise to use than attending a university course. (And a university course requires less expertise than coming up with QuickSort in the first place.)
when AI works well it is superior to Stack Overflow because what it replaces is not "Look up answer on SO, copy paste" but rather, look up several different things on SO that relate to your problem that you are trying to solve but which there is no exact definite solution posted anywhere, and copy those things together into a bit of code that you will probably just refactor a bit with a shorter time than doing all the SO look up yourself. When it works it can turn 2 hours of research into 2 minutes.
The problems are:
AI also sometimes replicates the following process - dev not understanding all parts of solution or requirements copies bits of code together from various answers making something that sort of works but is inefficient and has underlying problems.
Even with the working correctly solution your developer does not get in that 2 minutes what they used to get in the two hours before, an understanding of the problem space and how these parts of the solution hang together. This is the reason why it is more useful for seniors than juniors, because part of the looking through SO for what you want is light education.