Exactly! You provided very good examples. My original idea was that their user models were not generating good enough predictions, and someone said "maybe they already own it on Steam". Honestly, Steam has a very significant weight on this market.

The value of this "move" is not to collect general data, it is to collect specific, relevant and usable data, that relates to each specific user they have. I don't think that some sort of proof is required to have an informed and polite conversation about a topic. We don't even need to convince people to join our point of view.

- Can GOG collect data from Steam accounts? I believe it can.
- Can that data be useful to GOG in datamining efforts? I am very convinced it would be. (See nepundo's post.)
- Would GOG leave that data on the table and just ignore it, as a way to respect the user's privacy? I think they would say something regarding that issue if they did.
- Can I prove that they are collecting that data? No.
- Would it be silly not to do it, from a business point of view? Yes, quite silly.

Maximize their proffit? That seems obvious to me. How? Either selling less games for more money or selling more games.
How does the data from Steam help them on this task?

Say, for example, that you are a big fan of a game called Sim Sardine, a fish simulator. You purchased Sim Sardine 2013 on GOG during a promo for $5, with 80% dicount. GOG later came to introduce Sim Sardine 2014 for $30 and Sim Sardine 2015 for $40, but you did not pick it up. So the GOG heads say "Maybe we should aim for a lower price. This game does not seem to be very popular at higher prices. Should we knock them down?

However, due to GOG Connect, GOG discovers that you already own Sim Sardine 2014 and 2015, plus the Cold Waters, Acquaculture and the Fish Revenge DLC. You spent near $100 on them all. The GOG heads will instead say "Oh, no. There is money to be made from this. Keep the prices high. We were just too late with the other games."

ILLUMINATI 420 CONFIRMED

That wasn't funny, Mr e.

It wasn't funny because you didn't put :D after it.

I didn't even realize you can create a Steam account (in order to buy Steam games) without having a profile. Aren't they connected, ie. if you create a Steam account, then you have a Steam profile automatically?

Of course if you have no Steam account (hence, no Steam profile) at all, then all this is irrelevant to you.

Maybe I'll test this by creating a bogus throwaway Steam account, I created mine probably before Half-life 2 was released...

EDIT: Ok then, it does seem creating a Steam account, and creating a Steam profile, are indeed two different steps. Interesting. No idea if you can change the privacy settings without creating the profile.