Marketing departments everywhere do the same thing you are using to describe "growth hacking." They convene with members of other departments to construct the brand in a way that is cohesive with how the product or service operates (and should be perceived).
And not sure what you mean here. Growth hacking is not just about marketing. There are plenty of growth hacking initiatives for improving financial or business metrics e.g. employee retention.
Might want to read the book about Growth Hacking to understand the discipline and why it is getting more and more popular. It actually isn't just some lame name to describe a few marketing tricks.