Getting rid of customers and profitability

We had a session in our Business to Business Marketing class dedicated to customer profitability and how companies usually think that the first move is to get rid of what seems are unprofitable customers. 

A very important point raised was to be careful in how customer profitability is calculated, because the calculation will depend on many variables, such as the industry, the type of product or service being offered and the strategic importance of the customer (a big customer might be unprofitable by itself, but it might provide you with reputation to get new customers).

On the other hand, Seth Godin argues in this link that companies some times are afraid of dismissing customers, but there are customers that we need to get rid of if they are unreasonable, corrupt the system at a cost for other customers and distract you from providing excellence to reasonable customers.

At first, the two visions might seem like they are conflicting with each other, but I see them as a complement. If you include Godin's parameters into the profitability calculation then it will not make sense to retain those unreasonable customers that are unprofitable. 

How do companies usually get rid of customers? Increasing price.