This is the tragedy of the commons. It's entirely reasonable that Designated Origin rules prescribe the ingredients and naming of products, e.g. for champagne. The problem is that varieties cross polinate through air and thus endanger--oh my gosh--the traditional wine bread. That much I can gather although the article doesn't say so. It's probably a little more complicated, sure.

The article only says that hybrids from the 19th century were inferior; suppose taste wise. Which is a matter of taste, but likely reflected in sales. The upside is resistance to fungi and such.

Yes, there are modern hybrids suitable for colder climates. The rules have been relaxed a bit since.