I've heard that nonsense time and time again. And then there's this:
"G'day, cobber." "G'day, mate. How're ye doin'?" "Aw, been flat out like a lizard drinkin'. Hear the Sydney Swans hammered Collingwood on Saturday?"
"Ripper."
Cobber is archaic and you can always tell a Yank when they use that term.
Anyway, 'mate' is of UK origin and simply means friend. And yer mate is closer to you than your sheila or wife.
Oh, I am quite familiar with “mate”, thanks to some Aussie acquaintances. I thought that you might enjoy the article what with having lived o’er there.