I agree with the benefits listed above.
In addition, it allows the option of using snakeskins or similarly attaching the tarp to the CRL. The tarp is setup, adjusted, and ready to go, but can be rolled back into the skins for sleeping under the stars. If the weather changes, it can be deployed very quickly.
Of course the next question that comes up is whether to put the CRL above or below the tarp. There are many threads on that topic as well.