From the article it does seem that the failure of ability isn't strictly related to computers per SE, but to an over all inability to think about the word problems given in an abstract and mathematically coherent way. They seemed to ask participants to solve what are essentially database query, reading comprehension, critical thinking, and logic problems in the context of an email suite. Word problems can be hard for anyone that hasn't studied and practiced how to decipher them. It's just that using a computer kind of forces one to confront those gaps in what should be a fundamental part of highschool education. Math and science classes aren't just solving problems by wrote memorization or memorizing the periodic table, they are about problem solving. Lots of people fall through the gaps and don't get that one special teacher who understood this.