I think there is a world of difference in the "average total beginner" high school students taking a class to meet a district mandate, and the "average total beginner" self-motivated learners actually interested in computer science.
What about incomplete projects? Messy/hacky experiments? Completely idiotic/backwards stuff done for fun? Play-projects purely attempted for "ha I did it!"? Legally-grey (or blatantly illegal) projects? Or even school projects? I have hundreds of projects that fit in those categories, and none will ever be made publicly available. Sometimes it's just not good form to make a project public, other times it's clearly harmful to do so.
Nevertheless, I preserve my projects privately just in case I ever resume work on a whim, or want to reference what I did in the past (or more likely, what I did wrong). And now I can put them online privately for free, sharing with those I deem appropriate.