The reason they accept PDF is not because of the difficulty in getting tex files to compile on different distributions that I mentioned. Indeed, as they say on

The reason they accept PDF is not because of the difficulty in getting tex files to compile on different distributions that I mentioned. Indeed, as they say on the page you link to, PDF files created from a tex file are specifically rejected by the arXiv. Rather, PDF files are accepted for the (fairly small minority) of papers that are written using alternative editors like MS Word.