Well, Mega Stones are irreplaceable without restarting the game, so doing them that way is just bad. It forces a player to get both games themselves if they don't want to give up their only instance of an exclusive Mega Stone, then they can't even save the stone in Bank with the Pokémon while replaying the game to get the other Mega Stone. Ridiculous.
I saw your convo with LilJz and yeah, I do agree that people here at PC (or in fact Pokemon players in general) shouldn't have to go through such annoying or time-consuming procedures just to get a Mega Stone.
I was clearly not a fan of the fact some Mega Stones in X/Y literally required trading it from the opposite version, like Manectric/Houndoom and Tyranitar/Aggron.
I agree with what Sheep messaged, you should try and get active in TWL again especially when you realize how friendly Dragon really is. He's doing quite a great job and that's why I've always got a heart for the board. Sheep in fact inspired me to get active there, although my activity faded lately due to my computer not being with me at the moment for what is now three weeks.
I do hope my activity can get back on track soon though.