system
Given the following post, respond as if you're commenting on Reddit:
human
[Stargate] Why were the ancients so opposed to instruction manuals

Throughout the series technology left behind by the ancients is a running theme. The stargates themselves are a prominent example, as are Atlantis and the Destiny. 

However much of this technology is rather dangerous and left without instructions or safety markers. The only Stargate with a forcefield to prevent the kawoosh from killing people is Atlantis-- other locations don't even have a safety zone. 

Ancient repositories of knowledge can just grab your head and murder you with knowledge. 

Obviously this is danger stuff to leave around-- the goauld exploited the stargates for centuries to enslave humans. However even with a DHD there's no interface that lets you speed dial your favorite planet by name, or even a phone book.

I seem to remember some dangerous stuff in Atlantis getting accidentally switched on, while useful things like zpm factories and Stargate plans are hidden.
gpt
The Ancients didn't exactly plan out their own extinction.  They were suffering from a plague that killed every ancient in the Milky Way.  The Atlantis ancients fled to Andromeda to escape the plague, and ended up pressed so hard by the Wraith that they fled *back to the Milky Way.*    As a result, most surviving ancient technology is in the state it's in as an accident

Manuals probably  existed back a million years ago at the height of ancient civilization.  So did on the job training, safety measures, controlled access, and so forth.  These are all things we do in modern society to safeguard people against the machines we have that can very easily kill a person.  Most of that simply hasn't survived thr passage of time and lack of planning.