A whole variety of reasons including pre-existing momentum, a different feature set for issue tracking compared to other options, integrated mailing lists, bett

A whole variety of reasons including pre-existing momentum, a different feature set for issue tracking compared to other options, integrated mailing lists, better access control systems, more complex/more-featured project web hosting, better project statistics, better organized file downloads, etc. A very significant one is going to be avoiding the effort of changing platforms (from one to many different ones in some cases), but there are some nice technical benefits of the software they've produced. I think it's a shame that they struggle with uptime, stability, and maintaining a consistent management as there's a lot that's nice about their system overall (at least in my opinion).