Wine and beer are produced directly by fermentation whereas brandy and whisky require both fermentation and distillation. This is because

fermentation is inhibited at an alcohol level of 10-18%

distillation prolongs storage

distillation improves quality

distillation purifies the beverage.

Answer

distillation purifies the beverage.

Beverages like beer, wine are fermented but not distilled. They have relatively low alcohol content typically less than 100%. Hard liquor like brandy and whisky are produced by both fermentation and distillation. Distillation process purifies them and removes diluting components like water and increases the alcohol content.