It's a design compromise to keep it cheap as well as minimize the lane usage (i.e. no 2x lane configurations).Technically, there is.
Most of the 2x ports SATA 6Gb/s has a design flaw, it has 2x 6Gb ports but connected to 1x lane PCI e V2 (5Gb/s)
It's bandwidth not even 1/2 of what it supports.
It's strange!