PDF is an enormous pain in the tits to view on a phone and has significant accessibility issues for people using assistive technologies.

It's not even about blind people. People with ADHD or dyslexia use assistive technology, which frequently makes an absolute horlicks of interpreting PDF. It's one of the reasons I'm trying to move a lot of documentation at work away from PDF and onto just straight HTML.

Plain old HTML, with thin CSS on it to make it not be black-and-white Times New Roman. Kicking it oldschool.