No. Not true.
You can get by without IE. You can use a Mac even. This has been true for a few years.
I've been dealing with this shit for a VERY long time (and you have no idea about just how much pain I have endured dealing with Korean banking over the years). Think back to the beginning of Internet banking in Korea... (I even did work for some of the early payment gateways there and got to see the tech side up close from an insider perspective.)