There is no medical evidence to support the claim that hand washing is useless.
The WHO, as well as all major international health organisations, the EU and its national health ministries, clearly emphasise that "regularly and thoroughly cleaning your hands or washing your hands with soap and water or using alcohol-based hand rub demonstrably kills viruses on hands", which helps to contain the spreading of COVID-19.
The German Ministry for Health lays out in its protective-guidelines for patients, "to disinfect hands regularly" and in its current information on COVID-19, the German Ministry further states to protect from COVID-19 with "washing hands regularly and thoroughly for at least 20 seconds with soap and water". The same recommendations are formulated by the French Ministry for Health at its COVID-19 information page.
The WHO additionally states, that washing bare hands regularly offers more protection against COVID-19 than wearing rubber gloves.
Read more about the EU's response here and information from the EU about fighting disinformation.