Yes, alcoholic liver disease has been shown scientifically to result in allergic skin reactions, but this is a result of alcohol and not liver disease.
Have a quick look at published research papers, I was unable to find any papers which linked allergies directly to a damaged liver (namely those who have damaged livers then have food allergies as a result). There are many papers which discuss the impact of various foods and pathogens on liver function/inflammation (such as toxins and viruses) on healthy and inflamed/damaged livers. Such is the reverse conclusion which you have outlined as the response. If you have any scientific evidence indicating that liver damage directly results in food allergies, it would be interesting to read if you could provide details of the research.
Also, if one has food allergy/intolerance and then finds they also have liver damage, it appears from the information available that it may be coincidental rather than a causal effect.
Yes, doctors opinions do change over time as more research which is peer reviewed, and its findings, become available to the medical profession. It is no different to food allergies outlined in the ABC article. In the recent past, there was conclusions that the mother or infant eating some foods may make the infant more susceptible to some food allergies. This information was provided to parents based on the best available information at that time.
As more research is conducted, different outcomes to food restraint were identified and why there has been recent change in information from the medical profession. The information they give today is based on the today’s best available information.
If doctor’s relied only on anecdotal evidence from what is reported by their patients, and used this anecdotal information to treat others, the medical procession would return to the days of quackery. We are fortunate the medical profession of today is based on proven science and best available scientific evidence, as many diseases of the past can be readily treated with modern medical treatments.