After all, the majority of current mainframes have become a liability, which forces banks to come up with innovative solutions.
That's right folks, the legacy banking network runs on 1970's technology. Pretty much the only thing protecting your money is how crappy & slow it is, lol.
Remember the recent OpenSSL vulnerabilities? The main reason why almost no-one reviews that code is because the banks have an agreement with the OpenSSL people to write the code in a (apparently highly unreadable/eccentric) way so that it will compile on their punch-card computers. Bitcoin will soon be leaving OpenSSL behind for good, and hasn't relied on it for consensus critical code since 0.12.0.