Everything that a game publisher does, you can do yourself. But should you? It takes a lot of work, a ton of money and years of experience to consistently and successfully launch mobile games. It may look easy, but it’s not.
Technically, you can skip the dentist and can give yourself a root canal, but like trying to publish your own game, chances are it will be extremely painful, costly, and you still may not get it right before passing out. Sometimes it’s best to leave certain things to the professionals and game publishing is one of those things.