Lots of people (especially regular users) find the search function to be both more convenient, more informative and faster than posting a question. Another benefit is you get 'responses' from people who are no longer around or are not around right now.
If someone suggests a search it can be for reasons other than a lazy non-answer. Perhaps they recall the thread but are unsure of or forget exactly what the answer is.. As you yourself point out: "If all of us had perfect recall..."
If i see a question like "What kinda lube goes in this bike's gearbox", either I will have to search it out or the questioner will have to wait for someone who knows..
Suggesting a search to someone who is obviously not aware of the large volume of archives and the easy access to them is better than both options, imho.
Give a man a fish and you feed him for a day.. Teach a man to fish... etc.