I don't think it's totally unrelated, only having one or two third party life lines for charging customers in a currency other than AUD is fairly dire for the success of any "Silicon Valley" if the startups are planning on making any money from global online sales.
Do the fees that PayPal charge really cross the line from a possible business idea to non-viable one for you?
There may be some sectors which you could say you can't compete in on a global stage from Australia because of payment processing fees but it really wouldn't be many. What is the big deal about setting up a US company to handle it? Why not charge US customers in USD?
There are so many options that to dismiss running a business from Australia because of the extra few % really may be a problem in your business plan and product instead of payment processing options/cost.
I think you found the answer in your question. If I have to setup a US company because I can't get support in Australia to accept USD on my site, what else should I be doing in the US? It's got nothing to do with business plans or PayPal fees, it's about offering a professional solution on a global scale.