Because both take place primarily in a confined space? And both feature a rooftop scene and a drug dealer? They’re the same movie, basically.
To be fair, I do like both, very much. But I would not start a recommendation of The Room with, “Well if you like Kevin Smith’s sharply critical dialogue spoken by people who don’t sound like they’re trying to swallow half a ham steak, and scenes that follow one after the other in a logical pattern to create a cohesive whole, then you’ll love…”