(already had a feeling that someone will say this)
I won't delete my posts/comments because I want to be helpful, that's it.
But if I prefer deleting my posts/comments, I will archive it instead.
I respect what r/ArtFundamentals did, and it should be an example: After reddit's APIpocalypse, they don't support reddit and decided to close the subreddit. But the advices from the subreddit wasn't gone--in fact they actually archive it in their own website:
Wikipedia is an internet gem