Idk, I'm in my mid 30's and I've never had a moment where I've been glad to see something on SourceForge.
For whatever it's worth, which is probably not much, I'm in my late 40s and I never really liked sourceforge either. Too many clicks to do anything (still true), and I didn't like cvs (also still true, but thankfully now irrelevant).
(My SF account dates from June 2004. I expect I was thinking about using it as version control for a FOSS project I was working on at the time, though I don't know why, as it seems SF didn't support svn until 2005. Maybe I couldn't find any better options? The pre-GitHub ecosystem was pretty bad! But, luckily, I ended up not having time for any FOSS stuff from about autumn 2004, so: problem solved. And when I next looked, in early 2010, everything seemed to be git+github, and all the better for it.)
(To quote a famous TV series... :-) Oh my sweet summer child
So you were ~10 years old. I'll assume not a heavy user of Open Source software, at that time.
Edit: 2001, I see one (1) banner ad, and that ad was seemingly for an OSDN (Open Source Developer Network) conference. https://web.archive.org/web/20010517002942/http://sourceforg...
Given SourceForge only hosted Open Source software, and had no source of revenue beyond ads and sponsors for quite a long time, AFAIR, I think they get a pass on a banner ad.