It provides mailing lists, forums and isn't locked to a single type of VCS (in fact it doesn't even need a VCS at all, you can just release files - or you can host the VCS elsewhere and use it only for releases as, e.g., Free Pascal is doing with having the code in GitLab but all releases in SourceForge). Also as a user it has reviews and the project pages are not frontloaded with the source code but instead a summary that tells you what the program is, review/scores about it and even provide options to get notified whenever new versions are released. Hell, it even has screenshots.
Of course it all depends on each project to use them and IMO the SourceForge UX is far from ideal (also the pages load slowly), but at least the functionality is there.