I should have said "some fans" though, not "most fans". No idea about the actual distribution. I can say for myself, however, that I think of pre-2010 Opeth when I say that name.
Them being desperate is also an assumption, as is thinking that the growls are there solely for the sake of buzz and not because it fits the themes of the album
How do you know Opeth are frustrated? Admittedly they've made a big deal of tellign everyone the growls are back so maybe they are desperate to draw back their older fans. It's not working with me though.