ELI5: Why are so many old websites hosted at universities like MIT?

I Googled for the lyrics to "You're a Mean One, Mr. Grinch" and up came this ancient HTML document from the days of Web 2.0.

I've noticed that Google will often point me to these very old, rudimentary webpages that are 20 years old or so, and often hosted at American universities like MIT.

So my question is, why do these websites exist in the first place, and why do they still exist?