True, but the Galileo IS billed as a microcontroller and IS billed as being arduino uno r3 compatible. The Galileo is not billed as a "full fledged computer". What you are saying is that the OS running ON the Galileo is not designed to support RT operations and in order to do simple RT calcs one needs to build a RT interface.
You answered the question, sort of. In order to run the DHT sensor on the Galileo, one must create a interface that handles what the Galileo cannot.