I don't particularly like the proposed solutions for handling content that was valid but obsoleted. Of the available solutions, I am partial to editing in a disclaimer about the content of the question/answers being obsolete, or answering the question with a more current answer.
Here are some things to think about:
- If the accepted answer is wrong, so be it. This is not a problem localized to these questions. Downvote incorrect information. Just because it has a green check mark does not make it correct.
- If a better answer to the question is now "This isn't possible," then so be it. There are a lot of questions on the site that are answered in this fashion, obsolete content or no.
- Closing is a temporary state while questions are improved or are waiting for deletion. When correct answers to the question would be harmful somehow (ie, advocating piracy, leading to extended discussion, etc), then closing is a good recourse.
- Protection is appropriate in cases where non-answers may be posted by people who don't know better. It's possible for this to be done to any question, especially popular ones.
- Historical lock is intended for questions that used to be allowed, but don't actually reflect the current community consensus of what is a "good question." It's there to preserve content that has value, while discouraging future copycat questions. (Our community has not been terribly receptive to historical lock, historically.)
- Deleting has all manner of issues.
I'll tackle deleting in more detail. Deleting is bad because:
- Sometimes dead content comes back. Minecraft has a pocket edition and an Xbox edition that are both out of sync with the PC version. Perhaps something that is out of date for one is not for one of the others. There are lots of examples of stuff in games that was removed and later (frequently due to fan outcry) readded.
- Sometimes dead content is interesting. Say someone asked about something that was then removed from the game. Probably there are other places this thing was discussed, in a less updatable fashion. Wouldn't having an answer that says "This is dead, and was replaced by XYZ in patch 1.23" be useful information to have? Think if you're following a tutorial that is out of date, and it references something you can't find in the game. You google search and find an Arqade question that says at the top "This was removed in a patch" - that's useful!
- It requires moderator intervention, or significant community coordination. Deleting is one of the highest order privileges. There are many things that are easier for the community to handle. Given the current alpha/beta/preview release culture in gaming, it's safe to assume that content is going to bounce around between obsolete and current regularly.
- It is one of the hardest post modifications to recover from. You lose the content in a massive pile of deleted posts, and there's really no guarantee that deleted stuff will stay in the "SE Recycle Bin" indefinitely.
Finally, it's in opposition to previous community agreements on the subject, such as:
Can we stop closing questions that have become obsolete as "Too Localized"?
Here the community seems to be saying "Don't close this obsolete content, and certainly don't delete it."
Should questions about obsoleted mechanics be simply removed?
Here the highest voted answer was to close it as Too Localized (seems to have been superseded by the other question).
How should we deal with out of date questions/answers?
Here the highest voted answer used to be "edit it into the question/answer" but that was changed at some point. More recent answers seem to support "Too Localized" but are also prior to the discussion in the first question.