Often the mutation might have performance benefits. Of course if you're Rust the stdlib and compiler might conspire to optimise an operation you wrote which re

Often the mutation might have performance benefits. Of course if you're Rust the stdlib and compiler might conspire to optimise an operation you wrote which reads as non-mutating into an actual mutation which was faster. This is another benefit of the "destructive move". If I consume X and spit out Y, the X is gone, so it's OK if secretly I just mutate X and tell you that's Y now.