It's how people incorrectly get the idea that bands like Evanescence, Flyleaf, etc are all "goth" rock bands just because they have a female singer.
And it's really infuriating to fans of gothic rock, which really has very little to do with anyone's definition of metal. I have never, ever understood where this idea of operatic/dramatic female vocals + symphonic metal = goth* came from. Female vocalists in goth bands are more like Siouxsie Sioux than Tarja. And there isn't a lot of symphonic arrangements in goth (there are sometimes, but not to the extent that identifying it with gothic rock is appropriate). Don't get me wrong, I like several of the Sarah Brightman-metal acts (that's not an insulting term, either, just more appropriate than "gothic metal"). But that's because of my love for heavy metal, not my love of gothic rock.
* and whatever it is that Flyleaf is doing, for that matter. The term "gothic" is losing all meaning if that is getting lumped in.