Blue mage is a waste of potential, change my mind.

[Arrius]

Then the problem is SE locked BLU skills behind those non-soloable dungeons.

Then it could be, again, a translation error in the explained text.
Instead of 'Not suited for Parties' it could've meant 'Not being able to form/join Duty Parties'.

Again, could be hair splitting in my opinion and SE not have worded out properly, thus receiving the fallout of their decision to word it like this.