few questions about successful mobile games

Is it true that developing a mobile game without the helop of a renown publisher, a game has only 1 chance in 20 to become a hit?
What if that game was really good and innovative, does it still have the same chances?
Can mediocre games make it to top charts only because of strong marketing?

Is that also the case in PC game stores like Steam?
And what's the difference between mobile game store users & PC game store users?