This claim is true.
According to American Addiction Centers, alcohol is a depressant causing the nervous system to be suppressed: suppressing circulation and nerve-ending sensitivity. The article also points out that there is a high association between consuming alcohol and having erectile dysfunction. The article states that "Alcohol dehydrates, taking away the blood and oxygen flow needed to bring greater sensation to the genitals." This dehydration causes, "decreased blood volume and increased angiotensin, a hormone associated with erectile dysfunction."
AmericanAddictionCenters
An article written by a Urologist on WebMD explains how alcohol is a depressant but also a sedative. He brings up a historical fact "Before the development of the first true anesthesia in 1846 at Massachusetts General Hospital, surgeons routinely relied on alcohol and bullet-biting to carry out operations. Drink enough of it and alcohol can numb sensation to the penis to the point that it can be hard to get and maintain an erection." Making it apparent that alcohol slows the nervous to the point where in the early days of the medical field, alcohol was used as a sedative during surgery.
WebMD
A scholarly article from JAMA Network fact-checks the claim that the Urologist made that alcohol was used as anesthesia saying, "The use of alcoholic fumes for anesthetic purposes is recorded as early as 1513."
JAMANetwork
This claim is true because scientific claims have been made by irrefutable sources, alcohol affects the nervous system where erections rely on nerve endings and blood volume. Alcohol has been used in history as a numbing agent and sedative for surgery, showing how strongly it affects the nervous system.