Real explanation, just cause there may be some ppl that are genuinely interested, as opposed to just wanting more rings:
A limit on the number of accessories most likely originates with D&D/RPGs. Been that way for a long time. Besides being a balancing mechanic, the 'explanation' for it in game terms was that magical devices in too close a proximity would cause interference with each other. So one ring on each hand/set of greaves/gloves, one amulet, one belt, one helmet/circlet, etc.
that's actually a really nice explanation, would've been nice if this could somehow be added in the description of baubles, as it'd make a pretty interesting addition to the story
but with that it'd be cool if you would receive a bonus when you wear certain jewelry with eachother, as they'd boost eachother's properties and would become stronger.