Where "deep crypto skills" refers to someone who bothered to read the documentation on Solidity (the Ethereum contract language), specifically the section on function visibility[1], and the Parity wallet contract itself[2].
In other words, an obscure security hole was not found by a genius hacker. An obvious, trivial, simple mistake was exploited for $9m because the people investing money in it provably didn't know what they're were doing.
[1] http://solidity.readthedocs.io/en/develop/contracts.html#vis...
[2] https://github.com/paritytech/parity/blob/4c32177ef3f4521c66...