3. Lots of code is useless because it serves as some specific compatibly for an ad hoc process that someone a long time ago automated wrong.
4. Publishing code to GitHub requires effort in making it look readable to someone who isn't doing what you're doing.
5. If you don't do #4, you'll clutter up search results for others, which is literally a disservice to open source.
Also, public repos are for getting lots of people to work together for the good of the project's utility. Making them public for others' plaudits is literally the worst thing to happen to open source development.
Save the vanity for Facebook. We're trying to solve problems here.