Because I'm in Tasmania and the only trees that grow around here are gum and wattle trees and I don't think I should be putting bluegum in with anything other than Australian natives.
As for rocks all the rocks around here are just lumps of dirt or clay so once again, not going in my tanks, plus I like the look of the tigers eye and won't find that just bumming around my local stream lol
We're not all lucky enough to be able to just collect our décor, do you really think I'd spend hundreds of $$$ on goldvine wood if I was comfortable putting bluegum (which IMO looks nicer) in my tanks?
I can get three more rocks for less than the price of a butterfly fish... I'll pass.