You make this sound like someone with an IQ less than 120 is mentally impaired.

An IQ of 100 is defined as the median IQ level for a population. The range between 90 and 130 covers the whole gamut of human intelligence that's commonly considered normal.

Much of the day-to-day work in IT often doesn't need original thinking but merely skillful application of known methods and patterns, which in turn doesn't require a college education.