I cannot speak to whether the author of the piece in question is a book hoarder. I _can_ say that this is silly:
"How many books does a person have to own to officially be labeled a book hoarder? According to Shelfari’s Compulsive Book Hoarders Group, the answer is simple: 1,000 or more."
Please. While I am happy to say that 6ish years into reading primarily e-books, the p-book collection is under 1000, but I wasn't a hoarder before. I know, because this is a decent source on the topic of hoarding.
FWIW, I do, actually, know what houses of hoarders look like. There are lines of undrivable cars in front of them with no license plates, flat tires and moss growing on them. There are piles of things in the yard or driveway, but definitely _outside_ the house, covered only by a tarp, that remain, seemingly unmodified except to grow in size, for months. If there isn't any exterior indication and you are trusted enough to enter, there are paths between towering piles of stuff that otherwise fills the rooms top to bottom. There are _some_ paths -- some rooms are completely filled and in order to enter them, you would have to pick your way through the pile at the entry, or come at it through a window, perhaps.
1000 books does not make a hoard.
There is some reason to believe the author of the piece has a more realistic idea of what constitutes hoarding, and perhaps her description of books and her difficulties with them given a peek into the interior life of a hoarder. But that one hard number at the beginning, so powerfully mistaken, makes it hard for me to assess the piece with anything like fairness.