Yes, and a chance to get rid of any weeds.

Earthing up is mainly to stop the topmost tubers turning green in the light. I grew them successfully last year without planting the tubers, just laying them on the soil and covering them with a rotted straw mulch. I kept covering around the plants with mulch as they grew. It was a very successful method when it came to harvesting and yield, but I must admit there were more tubers gone green than should have been the case. I'm back to earthing them up this year.

From my experience earthing up is essential, the earth gets warmer on the sides, producing better tubers, also in wet weather they stay drier which helps when potato blight starts.

We suffer a lot from summer drought here so I guess the keeping them warmer and drier doesn't apply, Doctorbob, but I must agree they look better and seem to be growing better now they are all earthed up.
One plant had dead brown edges on the leaves, and I'm very concerned it could be blight already, especially as the weather is warm and showery.
I've pulled the affected leaves off but I may have to spray with Bordeaux mixture if the weather doesn't go dry, otherwise it always spreads to the outside tomatoes too.

We have had very hard frosts here, many have already lost some of their crop. Even though mine were covered with fleece, the ends of the rows were singed.