It’s even more of an issue if you work in a Windows shop and post to Linux webserver, or vice-versa.
If you use a not so smart FTP and transfer files to and back, sometimes you will end up with double spacing between paragraphs. Or maybe, all your end of lines just disappear. Or it may be that the transfer converts the extra end of line characters into unknown characters and you end up with big ugly questions marks all over your web pages.
It also causes problems when you use multiple OSes and transfer files between them. What a pain.
It’s too bad we don’t have some benevolent standards community that can just tell all the OS companies to use one standard for newlines. It would save the economy 10s-of-thousands of developer-hours. They could do something useful instead of detecting and converting newlines.