That's the crux of it, if the Voice is advisory only then it will be ineffective in making any meaningful change.
If however the Voice has powers to veto & make changes to policy / implementation then it would be able to make meaningful changes by overriding the democratic processes & laws that have been in place for 120+ years.
So a YES vote will either achieve nothing or destroy the Australian democratic system as we know it.
If the YES vote gets up the people who will benefit the most will be the lawyers.