The actual number is more like 16 fonts (~500kb total), excluding the decorative dropcaps which are only 4kb each. This is one of the largest & most complex pages on gwern.net (even after splitting out much of it to gwern.net/gpt-3-nonfiction ), so, it pulls down pretty much every font. (Even the backup fonts, because of the emoji.)
As for why we use those fonts, well, it's not like we didn't consider using just system fonts, but you run into problems as soon as you have any ambitions: https://gwern.net/design#webfonts
Never seen anything like this.
We've fixed the blanking of collapse regions with noscript... we think. So it should at least be visible. But you should know you're going to run into other errors because JS-less is not supported and is hiding an ever-increasing fraction of the site from you, between annotations & transcludes.