She really is in a way. But Marco isn't necessarily the type of person that gets paired with a MPDG. If anything, I think she's sorta imperfect, and has alot to learn. The fact that she has a lot of maturing to do helps with that. Usually a MPDG swoops into the MC's awful depressed life and forces him to live again, bringing out his true personality, allows him to love himself and others etc etc. I feel like Marco is as big of an influence on Star as she is to him. And in a way, I think that, yes, it's a great way to have a trope but do it right.
Either way, I'd love to have Star in my boring and mundane life.