I think it is important when talking about these things to distinguish between community rules and “official” rules (Pirates Code is for all intents and purposes, official). Oftentimes when a game goes out of print, is discontinued, or loses support, the player community (if it survives discontinuation of the game) will group together to create and maintain a community rule set. This was the case for many Games Workshop games (Blood Bowl, Necromunda, Battlefleet Gothic, etc) before a recent company push to bring some of these games back.
A community ruleset is nice because it allows the active player community to make necessary balance changes/rulings for games where the company failed to do so. This could attract players to the game as it shows that the playerbase is active enough to keep playing and improving the game. And as long as the community ruleset is kept entirely separate and distinguishable from the original ruleset, there should be no confusion for new/current players.