This is a fair point, but if she had done exactly that, she might've been one more nameless singer posting songs on YouTube or SoundCloud unless she really wanted to take it further. If memory serves, she had pretty much gave up the idol thing until they ended up calling her after she went back to America. The only reason why people tune into it is because she's signed to one of the biggest record labels in Korea.
Obviously this post is bait because who's seriously thinking that Yunjin, a brand new idol in a brand new group that hasn't even hit a year old yet, is doing "more" than the clearly legendary and influential group Blackpink? Especially when there's a good chance that Yunjin herself wouldn't dare think something like that, even in a room by herself. Even someone like Soyeon, who wears many hats when it comes to G-Idle, still has to answer to Cube at the end of the day. Sometimes change happens internally.
But opinions like OP only serve to set Yunjin up because of course people are going to be skeptical. It's one thing to say it, another thing to actually be able to do it, and it also depends on what kind of change she's wanting to implement... Which will obviously take time.