This makes no sense given that blocking happens before parrying. That reduces the value of a parry point considerably. (you've also done your math incorrectly unless you're using numbers other than the ones you posted).
If you have a 30% block rate and a 30% parry rate you're going to parry about 18% of the time (that is 30% of the unblocked 60%) for a total of a 48% chance to do some mitigation.
But 30% parry on a warrior means you're going to parry 30% of the time. So a point of parry on warrior is 1.7ish times as much mitigation as it is on a paladin with 30% block rate. Obviously this number changes with block rate, it it would always remain that parry does more for a warrior than a paladin.