This is recognized within the horror fan community as well. There are lots of people on various forums talking about the cornucopia of great horror at the moment, and my guess is a number of fans will spend years catching up on their expanding lists of films to see and rewatch. It's really remarkable.
There's a broader context that I think the author is missing, or at least ignoring: film and visual arts critics don't care about genre, they care about film. Genre tends to create a comparative context that doesn't necessarily exist if your scope is film at large. So, horror films exist to cater to a horror film fan base, romantic comedies exist to cater to that, superhero films cater to that, science fiction, fantasy, and so forth and so on. If it is a backhanded compliment, my guess is the same could be said of any genre to some extent.