it's been there since alpha.. since forever
the seeing mobs through walls by id tag I think was added later to the screen's features.
either way, it is too much power/knowledge for a game.
BUT they don't have a proper map system so yeah people used that f3 coordinate feature.
regardless.. it removes any dramatic tension in the game when you can simply hit that key even by accident to be shown all the monsters in the general area. they only have a numeric key so you cannot tell what they are, just that they are there.
bleh. I'm getting sick of the game primarily because he'd rather add beds and pistons (which would have rocked had his fuggin redstone repeaters/clocks not shit the bed on chunk reload ) than make it fun and feel like a game.