I think most of the forum is off-base on this one. In Japan, idols will show up for all sorts of open talent things on TV, even if that thing is completely ridiculous and has nothing to do with singing or dancing. And the point of an idol showing up is not expecting, or even hoping to win, but to show themselves and their personality, have some fun and maybe get a few new fans in the process. If, say, a Hololive talent shows up at Fillian's contest, they're really good but don't win and you think they should have, well, it's a pretty easy step from there to want to start seeing more of that talent and what they can do and supporting that talent yourself.
For an industry that is supposed to have developed from Japanese idol culture, I'm a little disappointed that this part of idol culture doesn't seem to have been bought along.