In my experience with my other open sourced stuff on Github, others fixing stuff is very rare. Having issues enabled quickly turns into users demanding fixes and no amount of asking for others to chime in aiding with pull requests actually result in pull requests.

IIRC most pull requests come either out of the blue for something new no one has requested before, or they don't come at all until I explicitly say "I'm not going to fix this" and close the issue.

Because allowing issues creates an expectation that the original author is keen on fixing them.

Fork it and add an issue tracker if you feel it's really necessary. That's the beauty of open source!

Because the dev is assuming that if he does this, people will use it to bug him, as opposed to using it as a request system aimed towards others.

Then they can fork it and allow people to post issues on their fork... but this does get me to thinking about how many people even involved in the FOSS world don't understand it very well. Perhaps I am the one wrong here.