Moderators can turn archiving on or off in subreddit settings. That dictates whether someone can comment or not comment on posts older than six months.
Edit: it is now interesting how much power subreddit mods have over AI in the near future. Have a lot of disinformation in your subreddit? Lock it, and screw up the billion dollar AI.
Edit: it is now interesting how much power subreddit mods have over AI in the near future. Have a lot of disinformation in your subreddit? Lock it, and screw up the billion dollar AI.