Blue
Ravenous Bugblatter Beast of Traal
To me, as a DM, it creates more work for a player to ask me what their character knows. I have the rest of the world to run. You run your character.
The DM is the interface between the world (including the characters) and the player. History, nature, arcana, religions are skills for a reason - the character lives int he world and experiences it, but the player does not. So there's a way to determine what the character knows that the DM has not yet shared with the player. Just like perception might share with the character that their character is getting pickpocketed - something else they wouldn't know without the DM.
Characters experience much more then the DM tells the player, ad sometime the player wants to draw on that knowledge. "Hey, we just spent a week of downtime in this city, have I come across a place I could buy healing potions?"