Consider the following article on Markov chains:
https://en.wikipedia.org/wiki/Markov_chain
and generate the pdf out of it. Starting from the chapter 'Transient evolution', most of the mathematical expressions are not displayed in the pdf. Some of them are partly displayed (like some glitch), some are not displayed at all.
This does not send a good signal, and one would become paranoid of checking if all its pdf-generated articles from wikipedia are well rendered compared to the real on-line articles, especially with math expressions.