Here's why:
* It's versatile: "Aloha" can be used as a hello, goodbye, and even an expression of love or affection.
* It's widely understood: Even if someone doesn't speak fluent Hawaiian, they'll likely understand "Aloha."
However, there are other ways to say "greeting" depending on the context:
* "E komo mai" (Welcome) is a good choice for welcoming someone into a place.
* "Malama pono" (Take care) is a good choice for saying goodbye.
* "Aloha kakahiaka" (Good morning) and "Aloha auinala" (Good afternoon) are specific greetings for different times of day.
Ultimately, "Aloha" is the most common and versatile greeting in Hawaiian.