The main criticism that other authors and strategists have regarding Porter includes their perception of the Five Force Model. They regard it as lacking justification. The choice of the five forces appears to be arbitrary and it is not an exclusive or exhaustive list.
There is no indication by Porter of how to assess the relative power of the forces or to determine what counteractions can be taken.
Critics feel that Porter’s work lacks empirical evidence to support his conclusions and many feel that Porter has a reluctance to interrupt his text with notes and references and his bibliographies are short, suggesting that it has not been well researched.
There has been much criticism regarding his Five Forces but less regarding his three generic strategies. The concepts of differentiation and focus (segmentation) have long histories in marketing and can be justified by the number of articles and publications, which appeared before Porter’s work. It is felt by some that cost leadership is not a strategy at all since operated alone it has no value and therefore it cannot be considered simultaneously with the other two.
Porter describes an industry as a group of firms producing products that are close substitutes for each other. One of the weaknesses of Porter’s work according to Winfrey, Michalisin and Acar is that his framework for identifying industry boundaries is an arbitrary process and does not address the relative proximity of competitive threats
The Five Forces model is static and cannot capture what occurs during periods of rapid change in the environment of an industry and some argue that there are no periods of equilibrium within an industry.