As a junior dev, I loved to ask interview candidates to implement merge sort or quick sort on whiteboards.
replyAs a non-junior dev I realize how stupid that was.
I think the first enlightenment is that software engineers should be able to abstract away these algorithms to reliable libraries.
replyThe second enlightenment is that if you don't understand what the libraries are doing, you will probably ship things that assemble the libraries in unreasonably slow/expensive ways, lacking the intuition for how "hard" the overall operation should be.