When someone cannot read or write in their native language, they are considered functionally illiterate. This level of illiteracy means that they subsist in their daily life through their ability to speak fluently, and recognize certain written keywords. Illiteracy is not a sign of stupidity; in many cases it is the result a lack of opportunity to learn. However, illiteracy does stunt the potential of otherwise bright people. The sad fact is their inability to participate in society through the mastery of language makes them at higher risk of being in poverty and committing crime.
As with illiterates in the wider world, illiterate developers are not unintelligent. Often it means that they didn’t have the luxury of taking a deep dive through the mechanics of the programming language. Many illiterate developers are practicing software professionals, backed into a corner by impending deadlines, or lack of resources. Perhaps they started in other fields such as graphic design, or business and find themselves scurrying along the surface of the language, learning in fits and starts as they go along.