[swimfar]

Did they share the program with other people? Why did 6+ people all rewrite the same program? Or did they have different specific uses?

From the first example of the article, it says that within the time span of one semester there were 8000 students who had used the software. In another example, the site used to compare courses at Berkeley now has over 50,000 registered users. Berkeley even paid them for the website afterwards because of the value they saw in it. They all produced something that lots of students use to solve problems/increase efficiency in academic life. That's not a trivial thing to do.