From a package deal I got a second copy of Bob Came in Pieces from Steam but Steam wouldn't give it to me, they said I already had it in my library and they discarded the second copy.

Which is a shame as I was hoping to gift it to someone.

But that got me to thinking that, for whatever reasons, I have a few digi games now that I can't use, no longer want or have second copies of and I think it would be awesome if digi distributors started allowing you to gift them even long after purchase.

Anyone know why you can't do this?

Kaching here comes the money train...

Probably more profitable to keep less copies/keys being "registered", and thus having to pay more to the developer.

But tbh i have no idea

prakaa's reason is the primary one. If you give your friend a spare copy of Bob Came in Pieces Steam and the publisher earn nothing... but if you tell your friend to buy it they get another $10.

This is also why another form of sharing games, split-screen, is becoming increasingly rarer on consoles; why earn $60 for 2-4 people to have fun when you can earn $120-240?

FWIW, GamersGate will always allow the gifting of duplicate copies. They will also allow the gifting of any game you have yet to download or request a serial key for. But for games you've played and no longer want, only Green Man Gaming allow anything near to gifting, and then only for select titles -- but for that privilege you'll have to put with their annoying SecuROM activation model.