What does the Australian scene have to do with anything?
Well any music festival needs big, overseas acts to draw a crowd. Obviously that's true.
Most festivals though also have several local bands on the lineup, from a range of popularity levels. It helps keep the local scene strong, gives some bands pretty big opportunities etc.
The Big Day Out had this consistently, and several Australian bands through the 90's and 2000's benefited greatly from the exposure the festival gave them. As they do at most other festivals.
Soundwave though gives almost nothing back to the local scene. Metal, punk, hardcore etc (especially metal) lack a great deal of exposure on the greater stage. Well punk goes alright from time to time, recently Smith Street Band and Violent Soho and the occasional hardcore band such as Parkway and Ammity Affliction get pretty big, but for the most part they're small, with metal almost completely ignored.
Now when you have a big touring festival such as Soundwave, that will bring punters through the gates to see big name bands (and Soundwave has been very successful in doing this) it represents an opportunity to increase the profile of these punk, hardcore, metal bands. Grow the Australian scene. Punters are there much of the day, they go see other bands, discover new artists during the day, it's one of the better things about music festivals - you come for the big names but get exposed to a heap of other acts along the way.
Instead, Soundwave fills not just the top tier, the top 10-20 bands with internationals, not even the mid range acts as overseas. Virtually the entire festival, from top to bottom is international. 6 of the 90 odd touring bands (+ 2 locals at each venue) were Australian. It's band 50-90, the ones that don't really draw the punters, almost all being from overseas that is terrible.
It's a massive missed opportunity as a festival, and it almost marginalises the local scenes further by giving no exposure to them.