To help our recollections, let's look at Sourceforge's browse page, from back in 2008:
https://web.archive.org/web/20081118033645/http://sourceforg...They did indeed host quite a lot of stuff, and it was undeniably popular as a place to get your binaries hosted free of charge.
But at the same time, is it being used as a source code repository? A lot of those projects don't show the CVS/SVN features. And sourceforge never hosted the biggest and most established projects, Linux and Gnu and PHP and Java and Qt and Perl and Python were all doing their own thing. And pretty much every project visible on that page had its own separate website, very few projects hosted on sourceforge exclusively.