I for example use a mixer because of when I use a service to buy Bitcoin instantly, I want my coins to be out of sight as the coins that I have bought have my details attached to it.
And that's exactly the reason for me to use a mixing service as bitmixer to get fresh coins that I can send to my cold storage, or to spend it somewhere.
Means bitcoin's transaction is not that anonymous as what other people think? Is it really possible to identify the dox of the user using his coin? How could it be?