It is probably
10% possible that intelli programs it in so that - Not doors, mind you - but levers, buttons, and other things that control doors can be "locked" to people not in the realm. That's as far as we're going with doors, and even that is a stretch.
We are never going to install a chest locking mod. It is your responsibility as a player to protect your items, we shouldn't have to make it super 100% safe for you. It takes all of 5 seconds to figure out how to hide your stuff: go far from spawn. Build a bunch of decoy chests and areas, etc. Chest-locks are a no-go

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Incidentally, if you are in a private realm, placing blocks above the chests "lock" them to the non-realm members.