I don't know if it's because jump potions, potd, or people straight up being bad, but I've seen a lot of players running around in gear (accessories specifically) that aren't for their main job.

STR isn't going to do much for healers and neither will DEX for melees. That CP ring might fill that last slot, but unless the boss requires a knitted sweater you're better off heading to the MB or vendor.

STR - DRG, SAM, MNK
DEX - BRD, MCH, NIN
INT - BLM, SMN, RDM
MND- WHM, AST, SCH
VIT- DRK, PLD, WAR

Granted, there's debate for tank accessories, but I'll leave that to the experts. This list is a general introductory guide.