Well there's that, and the fact that if you just paid yourself through some manufactured spend mechanism (eg Paypal family & friends, which a lot of people have been banned for but I digress) via consumer cards there's really no major tax implication, but paying your business via merchant account must be a bit of a nightmare, since it's going to land in the business account with associated merchant fees and you'd need to exclude the revenue to avoid double taxation but you'd probably be claiming the merchant fees so I'm guessing that one way or another the ATO/accountants wouldn't be a huge fan of it.