bansama: reference to developers of games, not websites
I know and am aware of the intention, but I see no negative impact on expanding the group.
bansama: Valve are not going to want a third party website trying to get a slice of their cake
But what sort of revenue are we talking about?
Advertisement? Steam wouldn't use any on their own pages, so there's no loss to them here if a third party does.
Or maybe fees? Steam would always keep their own charge on the trading system (assuming there is one, which I don't know), so any third party cut would be additional charges they don't get regardless of the means of transfer.
How else could somebody (ab)use such a system to get money out of it that Steam would be getting otherwise?