Really? it feels nothing like it honestly, source forge amongst other things started and ended with poor developer experience, in part they died from being outclassed.
For developers obviously only a small part of that is relevant but the service is not really primarily for developers and since developers "hold the keys" it makes sense that once services that care more about developers appeared many developers moved there. From a user's perspective it is sad though since pretty much every other supposed alternative does not provide a lick of SourceForge's features and the fact that there isn't any after all these years shows -IMO- how much most FLOSS developers care about their users.
On the other hand SourceForge always had a terrible UI, especially in its earlier days and while its current incarnation is the best its ever been (aside from the oversized elements) it still often feels like a mess of elements jumbled together and while they do provide a lot of useful functionality, it is often behind very clunky interfaces.
I wish there was a real alternative though.
Counterpoint: the readme (or GitHub.io site) in combination with lightweight features like the star count is a good enough replacement for all of the bespoke knobs on SF. OS app stores have also become a thing since SF’s decline and they’re a better route for most non-technical users.
I have never once been lured into clicking a sleazy download button on GitHub and I recall that happening on the semi regular when I visited SF back in the day.