They're not a joke, they're a product called Seawing, made by a French company. They're being being actively tested and can be retro fitted to existing vessels rather than requiring a new design.
Correct, I think they were saying it was being reported on as if it was a joke. Not being taken seriously as a good step towards reducing carbon emissions.
And they're a lot more advanced than traditional sails.
Traditional sails only work with surface winds, which are relatively weak. These giant kites can go much higher and take advantage of much stronger and more reliable winds at higher altitudes.
I'm not sure who they wrote that headline for. "Giant kites" is one thing, but what really stood out to me was that they added on the "reduces carbon emissions" as if that part would be unexpected. Like the whole point of these giant kites is to pull the ships and reducing carbon emissions is icing on the cake, rather than sails coming back because they are a carbon-neutral method of propulsion.