there is some incentive there. But honestly I do think psychiatrists are acting in good faith in their diagnosis, they are just wrong.
The effect, in my opinion, is a societal one. Most americans have developed personality disorders, its like living in a mental hospital. But since they are the majority, the overwhelming majority, it is the healthy people who, through societal gas lighting (being on the receiving end of people with personality disorders) they are convinced **they** are the ones who are broken instead. Psychiatrists tend to go along and look for reasons.
The end result is a bunch of people int he minority being diagnosed with autistm rather than the vast majority being diagnosed (more correctly) with the personality disorder.