To me, "growth hacking" evokes more than just marketing.

Let's say my startup hustles like crazy and carves out a deal with a major coffee chain (like Square did with Starbucks IIRC).

Suddenly we have access to a whole lot more users. We grew the user base drastically, yet it wasn't exactly a result of marketing but rather one of strategic dealmaking.

To me, that is the quintessence of growth hacking.