Why does the format of the content matters that much?
Is this proved that people putting knowledge into PDF files create more valuable content?

I see you're from Poland so you may read Quake Bible written in 2005-2007 for Quake3 (polish language):
http://www.stroona.neostrada.pl/kurna/BibliaQ3.pdf

However it describes most of the things specific to Quake 3 like installation of patches, mods and additional programs (e.g. server browsers etc.), but some parts are interesting and still actual :). It was huge thing back in those days now it's part of quake history.

Woah, I remember reading this years ago.

Quake: Live