I hadn't thought of this before, but whether a stat buff granted to the party is stackable (which I don't know) can make them a pro or con depends on the party makeup. If you have 4 casters and 1 Bard and 1 Monk and 2 Healers, then the Bard's DEX buff and the Melee's STR buff benefit no other players, whereas the INT and MIND buffs can help all the casters as well as the healers.

If these stack then a party with 6 casters where each one gets a + INT boost from the other 5 casters makes them even more powerful vs a mixed party.