I think this has to do with what makes a mental state considered an illness. I think the most important criterion is if the condition interferes with your ability to function in society. Some conditions, such as vivid and continual hallucinations, perhaps, would inferfere with your ability to function in just about any society, so will be continually viewed as a mental illness (even if the cause of that defect is attributed to non-physical factors, such as “touched by God”). Other conditions, such as mild autism, may be adaptive for some cultures and maladaptive for others. In modern western culture of gross specialication and independence, it is possible for someone with such a condition to channel that in a way that benefits society. In fact, there are many such avenues available. In the early 1900s, however, the market for someone who could perform tasks similar to those of writing very complicated computer code without ever interacting with other people was vanishingly small. So these people were stuck doing pointless repetive tasks, making no contribution to culture or the economics Even in the 1970s and 1980s, that was the case, if to a lesser extent. But today, is such a person truly mentally ill, as defined above? The answer is not so clear.