i will agree with you, graphs and numbers released from any company are going to be skewered to make them look better. its only natural.
but to play devils advocate, how many of blizzards 7+ million subs are unique subs? how many out of that 7 million are simply duplicates from people who buy a second account? i personally knew of several people in my guild back in TBC days that bought a second account and kept both of them active at the same time. what about the people who multi-box? while the population who do is, im sure, really really low the fact remains there are numerous people out there who own multiple accounts.
isnt there a guy who used to multi box like a full 40 man AV premade? again the population of people who do things like that are probably in the minority but thats proof that the 7 million sub number is a little misleading.