When I run games, I'm in charge of the world and the players are in charge of their characters. That's our roles. There shouldn't be any overlap unless invited by the person controlling a given thing. If the referee asks the players to help worldbuild, awesome. If the player decides on their own to worldbuild, that's overstepping. Likewise, if the player asks the referee to help with their character, awesome. If the referee decides on their own to "help" the player with their character, that's overstepping. The world is the referee's; the player characters are the players'. Period.
As mentioned, this helps with discovery and exploration. Really, it's the only way discovery and exploration can happen. If the players can just drop elements into the world, they're not discovering or exploring anything, they're just deciding the thing exists. To discover and explore there has to be surprise. There's no surprise when you dictate what's there.
Without the referee there's no game; without the players there's no game. It's a cooperative hobby. If anyone drops the ball, it doesn't work. Though the players have a far, far easier time. Their workload is orders of magnitude less than the referee.
Railroads are anathema to the collaboration required to play tabletop RPGs. Linear adventures, as boring as they are, are infinitely preferable to a non-game railroad. Sandboxes in the sense of the referee designing a world and dropping hooks throughout and letting the players decide which to engage with, is the best way to go as it gives maximum freedom to everyone involved and allows/requires the collaboration that everyone keeps talking about.