GUTTERS & DOWN SPOUTS

Why do we put gutters & downspouts on our houses?  They just cause ice to build up and water then runs backwards into the eaves and under the roof shingles.  If gutters weren't there, the melted snow would run off the roof to the ground instead of into the house.  French drains around the perimiters of the houses would direct the water away from the foundations, thus eliminating any water damage.  Sounds simple enough to me with my simple mind.