I imagine Vueling are targeting visitors too Ireland. Despite being by far the cheapest airline between Cork and Paris, nobody seems to know they exist. They have done very little to publicise the route in Munster and when it's the only route they have out of Cork, nobody is going to randomly discover it on their website as happens with Ryanair and Aer Lingus.
It's a pity you can't officially use them for connections at Orly, as flying into CDG and out of Orly as Air France allow is a pain in the backside that makes a Heathrow->Gatwick transfer seem straightforward.
Vueling is offered through the Aer Lingus booking engine. It directs you to Vueling website. Aer Lingus was well known for its Cork/Paris route.