It's not clear in my original post, but I was talking explicitly about what a programmer can achieve by themself, without any aid from peers/mentors. I don't think your example contradicts that. How many of your classmates actually did the project by themself, without getting aid from tutors/lecturers, discussing ideas with classmates, etc? And even if they did, the problem still isn't directly comparable, because you've presumably been discussing the ideas that you are using in your projects during the course. The ideas are fresh in people's heads. This is not true in the real world, where you can be assigned to working on a project that uses skills that you haven't touched for years.

Anyhow, our discussion is a little theoretical. In practice, I can say that what I described is really truly what you find when you work in a large corporation writing code. I know it's hard to believe, but have a look around at the horror recruiting stories on this site, or stories talking about how enterprises do software development. It's not a pretty picture. It's not just that your baseline programmer can only write a project of about 1000 LOC, but also that there are a significant number of "developers" that can't even do that. Hard to believe, until you've seen it for yourself, but true nonetheless.