There was a time where Bitcoins transactions were thought to be super private but unfortunately one should understand that with the upcoming years with the advancing technologies people have identified it to be pseudo transparent .
Right from the get go, the thought of bitcoin to be super private was only the thought of newbies and inexperienced crypto user because it was stated before that bitcoin procedure are run through an unprecedented range of transparency and all it transactions are publicly stored on the block chain.
One can actually trace the address and if a person uses the same address a lot of times
This are one of the precautions bitcoin user needs to stop doing but with the use of multiple wallet either some transaction which is hidden now can be unfold in the future and this is the reason why it good to use bitcoin mixer.