Yes, it may seem "inefficient" at first glance, but this people are trying to deceive you... In the end this design that's a tradeoff that was known in the beginning as in the end you don't mix for efficiency you do it for effectiveness of really breaking the past history of your accounts.

C'mon ask max why do they blend to work with chainalysis, and how many people have been caught by address reuse after using Wasabi coinjoin... Surely reusing addresses is super efficient and sleeping with the enemy to catch "bad guys" is too.