What were the main criticisms of import substitution ISI as practiced in Latin America?

If it is used indiscriminately regardless of industry and time, it will generate inefficient monopolies that will result in higher costs for the end consumer.

For example, Mexico used this industrialization strategy between 1940 and 1970, successfully achieving the Mexican Miracle. However, it continued this trend well into the 1980's, allowing inefficient monopolies such as Pemex (oil), Telmex (phone land lines) and Luz y Fuerza (electricity) to flourish. At the beginning of the 1990's high inefficiency and low flexibility meant Mexico's companies were not able to compete within an increasingly global world, putting a severe blow on Mexico's growth.