Bedrockgames
I post in the voice of Christopher Walken
Sure, and you can allow players to just pick whatever number they want to roll after they roll the die, too. Metagaming is one of those things that people tolerate or even enjoy to varying degrees, but if the DM doesn't allow it in part or in whole, it's cheating to engage in it.
But that depends on the game system. You can't just say meta gaming is always cheating, simply because you don't like it or because you play one game that discourages it (or even has a specific rule against it). I don't put any rules against meta gaming in my games. I leave that to the players and GM to decide amongst themselves. If they metagame, I wouldn't regard it as cheating. I think this is an odd position to take. Personally i am guessing we probably are pretty close in playstyle when it comes to meta gaming. I just don't see how allowing a player to metagame is the same as allowing them to alter the result of a valid die roll.