This is a very interesting topic of discussion.... I have a great example that I've only just discovered:
Mister Big T, I've only just found out about (cause he's started posting here on RRR XD) his games are relatively "popular", and until now I never knew about him and his games. Now I do, and I realize he's rather well known.
Games become a "success" because people begin to LP them, as a developer I want people to LP my games, as much as possible! This means that it goes around YouTube, and then more people will see these games and then they themselves will play them.
It's all about how much you Advertise. The more people that plays your game, or see's it around the more people will start to play it and the more successful it'll be.
Another example is Kingdom! It's very popular on this site, most likely because Lato is on this site
but if we were to ask other people about the game, they may not know as much about it!
It's also about connections! For example NicoB, he knows two well known LP'ers (Cry and PewDiePie) and so therefore, he becomes more popular. It's works the same way as the Game Industry
Sometimes it's not about the skill, it's about who you know!