I don't think it's a technological problem. There are surely talents in Europe that are capable of creating wondrous things (let alone social networks), see Skype for example (before Microsoft has ruined it). I think it's cultural -- USA is the center of western culture (like it or not) and many fashions/trends are born there that are later followed in other countries -- Hollywood, music (MTV in 80-90s), TV series, Facebook, Apple etc.