I recall this occurring with college registration websites ~25 years ago. In retrospect, I suspect it was so students registering online didn't have an advantage over those registering in person (at the time, home internet access was common but nowhere near 100%).
I had this happen at a local community College but it also was where you would access your grades. Shut down over winter break, was awkward to tell my internship coordinator that I couldn't access the website for 2 weeks to get my grades because the website was closed over break... Fricken crazy (and they where using a pretty popular platform, this was not some home spun system)