Arc welding has many preferable qualities in welding such as: Faster weld speeds (obvious economics). Less distortion from thermal expansion/contraction. Addition of alloying elements in the electrode flux or coating. Higher weld qualities since scavenging agents can be added that will combine a "float out" impurities. The gas shield from the flux or additional externally added inert gas shields the molten weld pool from harmful atmospheric gases such as oxygen (oxidising) and hydrogen (embrittlement). A better selection of weldable materials (extremely difficult to "torch" weld aluminum due to oxide formation and high thermal conductivity is one example magnesium will start to burn and is hard to put out would be another example).