Pretty sure they did well too, especially since Welcome Oblivion had the backing of a major label.
Also, Ghosts was the first Nine Inch Nails release after Trent split from Interscope for various reasons. With that in mind, which seems more likely? Trent doing an album of music that he wanted to, but couldn't under the pressures of a record label to produce hits, or Trent just throwing out some demo material under the Nine Inch Nails name in order to sell it? If Trent felt it was different enough from Nine Inch Nails, he wouldn't have put it out under that name (see: Tapeworm).
Like I said, regardless of what anyone thinks of it, Ghosts is a Nine Inch Nails album, and saying it "doesn't count" is idiotic.