There were four 'buckets' and they are very close to this color system. They are dominant driver, complacent, ego driven, and analytical. The idea is to, as quickly as possible, identify the customer's type, and adapt your sales approach to that. You learn to use a communication style for each bucket. Different types of questions to ask, different speed/ energy, different body language.
I was a terrible salesperson, but I watched the managers and top salespeople use this approach with much success. They would match their style of communication with the customer's, in an attempt to earn their favor and make them feel more comfortable. The hypothesis is this increases the likelihood of closing the sale.
I understand these buckets (colors) aren't scientific, and it sounds like some folks in Sweden might have taken it too far or been misled. But the article says
"Erikson has repeatedly claimed that the benefit of his colour approach is that it helps us understand ourselves and others and, as a result, improves our communication and reduces conflicts."
So I'm not sure that the idea of learning different ways people communicate, and in turn, how you yourself can communicate in different ways is a 'fraud'. To be fair, I haven't read the book so I don't know how or what ideas are presented.
I think the 4 buckets/colors can just be a loose 'framework'. As long as you understand it's not the end all - be all of personality. In fact it's not really 'personality' at all. It's just a quick and dirty way of grouping common characteristics of people.
Maybe it's not useful in all situations, but for some applications (like sales), there is certainly value in communicating with people in a way that is compatible with their style. In the case of car sales, it's very tangible value, a larger paycheck :)