One reason is discoverability as they have a rather extensive searchable directory of open source software.

Another reason for quite a while was binary hosting, which github originally supported, then discontinued, but finally added again in July 2013. Additionally, the ability to use any open source license or combinations of licenses, as Google Code supported binary downloads during the time github didn't but only permitted one license per project and only from a subset of open source licenses (originally a small subset, later expanded). Google Code, of course, is sunsetting now. And github now supports multiple licenses as well as binary releases.

I will second the Discovery aspect as being something that I like about SF when I first used it in the early 2000s. The reason I liked it so much was because I was a kid looking for free games to play on my PC, who soon learned to equate opensource == free, who then started browsing SF's games category (played a lot of BZflag).

That said, with projects and people leaving SF, and their UI leaving a lot to be desired, there are so many more options I'd first use for project discovery.

Oh right, the other reason I forgot to mention is lack of volunteer time/enthusiasm to deal with a move. If you already bounced between Google Code and SourceForge two years ago, chances are you're probably not completely excited about jumping ship to GitHub right now.

(But yes, right now, if you're on Git, GitHub will give you binary downloads and all licenses.)

Actually you can easily import your code into repos now. Also considering Google code is shutting down you can easily move your project to github from google code.

Github lets you use any license you want.

Right. I meant it as a comparison to Google Code, hence mentioning it during the time period that Google Code supported binary downloads but github did not.

GIMP did move off Sourceforge back in November 2013[1]. Unfortunately, because there were a bunch of links pointing there it still ranks very highly in searches for GIMP. I'm not sure if there's even any way to delete a Sourceforge project.

[1] See the top story on http://www.gimp.org/

You could remove all the installers, replace them with a README.txt, and update the website and project description.

That said, looking at the top story, I guess they consciously chose not to do that and then things went sour.

Doesn't matter. Someone elsewhere in the discussion found out what they're doing - Sourceforge now has a policy of taking over the project pages of projects that've moved off Sourceforge and running the pages themselves as mirrors (apparently with added extras in the installers): http://sourceforge.net/mirror/ If you remove all the installers, they'll just get them off your website instead. If anything, removing everything from the project page would just give them even more of an excuse to take it over.

I wonder if there are any OSS licenses with a legally valid "except for Sourceforge" addendum available.

OSS can just use trademarks to stop SF from redistributing the binaries under that specific name (thus will kill their search rank).

Good point.

Is it possible to delete a project on SF? I've looked and can't find any information on it (on SF... haven't googled yet).

Legacy, basically.