Henry Ford said “If I had asked people what they wanted, they would have said faster horses.”

The faster horses argument is saying you can’t ask people their opinions as they are hopeless at conceptualisation as they base all idea on their prior experience. This doesn't prove research is a waste of time. It only proves that if you ask stupid questions you get stupid answers. That’s why typical marketing questionnaires can be worse than useless as they fail to uncover new ways of thinking and, at best, validate what you already know.

The ‘horses’ argument is moot as any research should be designed to ascertain the users’ goal and not the task. For example, if you had asked people in the 19th century what they wanted to achieve they would have said they wanted to get from A to B as quickly as possible and avoid  smelling horse shit.

Another way of looking at it would be to interpret what people meant when they said they wanted faster horses. They were asking for an improvement in their transport system. Today a researcher would investigate what attributes were important to users, which would form the basis for further design research.