Everyone who is interested or would want to know about Yume Nikki has probably already seen or played it. The fandom hasn't died there is just no point in making videos. YN let's plays aren't that popular because walking simulator 9000 doesn't seem that interesting to people.
Speaking as a YouTuber who's let's played Yume Nikki and several fangames, they're just really hard to commentate on. When all you can do is wander around the same places looking for the same effect, you're gonna run out of stuff to talk about.
Can you link me to your chanel anon?
Also Yume Nikki playthroughs don't tend to get a lot of views, so that makes them more hidden in the ocean of videos.