It's not just RTD mode, these past-dependent theories have been in root since the series began. I was there in 2005 when people assumed "Bad Wolf" was Davros, or that Adam (the punk kid The Doctor and Rose met who abused his priveleges) would turn out to be Davros based on that hole he had in his forehead. In this instance, Bad Wolf turned out to be a new idea.
When Donna was hearing the Meta-Doctor's heart beat resonate through time in "The Stolen Earth", people mistook that for Donna's heartbeat and began making wild ideas that she was Romana or The Rani. It turned out to be a new idea
Last year, people insisted Omega was behind the cracks in time and was the "silence" and that River was in leuge with him because they THOUGHT they recognized an Omega symbol on her commando gear. What happens? The Silence turn out to be a new idea, and, and whilst her identitiy has been allegedly spoiled on the 'net (nothing's certain until the episode airs) that very spoiler makes River out to be some what of a unique idea too, though more of a conventional one to sci-fi if the spoiler is accurate.
You'd think they'd have learned their lesson by now, but they havent. They still come up with the most banal and poorly thought out theories imaginable, letting their inner fanfic author speak in the abcense of common sense, all in a desperate bid to see something else from the past rear it's head, instead of expecting and discussing any new ideas that test the scope of their limited imagination.
The theories just make the fandom look dumb and incapable of originality. That's what I hate