Pass by value of Eigen Matrix in constructor of DataHandlerCPU

I was wondering why we pass the Eigen matrix by value instead of by reference in the constructor of the DataHandlerCPU and thus creating an expensive copy.

template <typename data_t>
DataHandlerCPU<data_t>::DataHandlerCPU(DataVector_t vector)
   : _data{std::make_shared<DataVector_t>(vector)}
{
}