I have both a public and a private wiki, but most of my PDFs are 5000+ page instruction set architecture monsters, so I much rather prefer to view them offline in some decent viewer instead of viewing them in the browser.
I also have passports scans and other sensitive stuff. I don't trust that I can secure mediawiki well enough to put those in clear on the internet (in upspin they are encrypted with a local key and the storage is my own server, mediawiki is in the public cloud).