Which blockchain? bitcoin address has no names, one entity can own billions of bitcoin address if that is what you mean. What I say is based on my experience playing on this website.
Sure, but how do they get the winning seeds? They also prove that nothing is fishy. My user ID is in the low four digits, I have been playing there for years, and also never went over the third winning level. But with the millions and millions of users, these win posts are more than realistic. And as I said, the blockchain is proof.
FYI, Freebitco.in does not use blockchain for it's game. Blockchain is distributed and immutable like bitcoin blockchain. There are many web casino before that rely on bitcoin blockchain for results like satoshidice before it was sold in 2013, but there none now because they can't cheat ang go bankcrupt. Freebitco.in seeds were only stored on their servers and most users don't know about changing client seeds.