A vampire is both "immortal" and "the living dead". Immortality means that they don't grow old. If the hypothetical necrobrands never stagnate in their output, they can't grow old and thus uncompetitive.

A "vampire brand" sounds even more appropriate considering hypothetically it feeds on current trends and turns them to its advantage.

Then again, there's plenty of misnomers in the English language.

There is of course the word zombie

Zombies are visibly doing worse and not operating all that well. Vampires? They're slick, sexy killers and manipulators that people need to invite across their threshold.

They've probably attempted a portmanteau with "necromancy" but that sort of leaves out an essential connotation, doesn't it.

In old usenet/forum-speak, to "necro" a thread meant to bring it back from the dead, they're probably playing off this meaning.