Hard disagree. The power of YT lies in its recommendation algorithm. Do you know how people complain that they watch one video of <random topic they don't usually watch> and suddenly they get flooded with videos around that topic? It's a curse, but also a blessing. If the Youtube algorithm likes a certain video on a Vtuber's channel, any user that watches something related gets recommended that video. Which results on quite a lot of opportunities for that vtuber to be discovered.
On the other hand Twitch has shit for discoverability. There is basically no way to get randomly noticed, none what so ever.
On your specific usecase: You search for a new Vtuber to discover and use the site's search features, good on you, maybe even scroll down twitches result page to click on a smaller stream. I agree that Youtube's search is shit, and Twitch can be decent, but that is far from what usually occurs.
People hit "browse", click on a game they want to watch and then click on one of the streams on top. The first 2 rows. Without scrolling down. In 90% of the time.
If you are one of the guys dozens of rows down below with <10 views, there is no way you get discovered, no way to even show how you are worth checking out.