It is a fact that the liver is damaged by long-term abuse of alcohol; that is, not the alcohol itself when a small amount is drunk, but the excess of regular absorption of multiple drinks a day. This excess of alcohol causes scarring of the liver, and a condition called cirrhosis, where scar tissue replaces healthy liver tissue.
The reason excess alcohol causes this condition is that it overworks the liver to breakdown these toxins from the alcohol. Stopping drinking does allow some repair of the liver, but if it has occurred over too long a period it gives the liver too difficult a task and the toxins are not sufficiently excreted. Many alcoholics die from cirrhosis of the liver.