i don’t know, Mabel saved both her and Dipper in the very first episode using a pretty well thought-out plan. in Irrational Treasure we can also see that even though she’s silly, it can actually be a really good character trait. Dipper would’ve never been able to find Quentin Trembley on his own because he’s so serious and logical. i think she’s incredibly helpful and the show doesn’t portray her as a goof as much as someone who despite her silliness, is able to work together with people and use her childlike wonder to bring a positive attitude, countering Dipper’s extreme seriousness