Who gives a flying monkey's about the lore reason? People just want the items to wear or use, so slap in some rando shady merchant to give you a quest that takes you to some rando Allagan node that burps out items for gil; chalk it up to the Allagan Empire researching an interdimensional anomaly with only a small rift in the fabric of reality to stick their thermometers in - they only thing they got from it were random items similar to those of Allag yet entirely incomprehensible - so they replicated them, though they lost their original function... whatever that was... they did get to be used for a small time.

Yours sincerely - a person quite into Drakenierverse, as well as XIV's lore, who can discern when something is possible to be added for fun and something that can be easily written in.