Why -- for a report created in 1996 -- using TeX tools why does

https://www.gwern.net/docs/math/1996-hoare.pdf

look so awful?

Probably because the pdf was produced from scans.

Forget the software.

How did hardware get so good? When you think of many, many gigabytes of RAM, all those billions and billions of bits and it checks out as flawless, I am gobsmacked at the perfection.