I think you might be reading outdated information. There was a period of time when they would only allow MC for foreign bookings, but now they take most overseas credit cards.
The reason for it was likely due to security concerns - there are a number of entertainment & ticketing websites that don't accept foreign CCs due to a high rate of fraud and/or unwarranted chargebacks. I suppose OLC figured out how to handle it.
Phone reservations don't open until a month after online reservations do, so it's not the best idea to wait.