It's a by-product of the 20th/21st Centuries, over-sensitivity to natural fibres, in the same way as some people can't eat nuts, or others can't drink milk. The more civilised and germ-free our environment becomes, the more chronic reactions there will be. Already hay-fever is common amongst people, where a century ealier, perhaps more, they'd be considered oddities.
Ever thought, though, that some cats are allergic to people? A lot of cats in the western world are feral. Go to the Colosseum in Rome. The place is crawling with wild moggies - ironically they live where the lions used to be kept!
It's the common household moggie that's the threat. Affectionate, curling up by the baby in his/her cot, smothering the kid with its soft hairs.