Yeah, it seems like the standalone topic forums are disappearing. But also it seems like we've simply moved on to more pressing conspiracy theories. Faux astronauts may have been in vogue when we had less of a dire social and political situation to worry about. Now, perhaps, it's just quaint.
And along the other dimension, each individual forum -- as a community of humans -- will have a natural arc that waxes and wanes. As you can probably see, quite a number of posts we entertain are just the social banter of the long-time regulars. If nobody is going to come here and talk about hoaxed Apollo missions, then we'll debate American government, or children exploited by their parents in the entertainment industry, or non-controversial aspects of the missions and the preservation and curation of their artifacts. I guess it is what it is.