Because you irritated the snot out of the ignorant lunatic fringe element* who are drawn to these threads like a moth to a flame. What's worse, you refuse to engage them, and thus deny them the satisfaction of the illusion that their ill-informed notions and ideas are of equal standing with those of educated people. You refuse to play their delusional game, in which every thread starts over tabla rosa and they get to trot out their trite, already refuted arguments and pretend that they've never been assailed. You refuse to cater to their fantasy-reality, in which their ill-informed, recycled arguments are deemed to have merit, and their intellect and knowledge is on par with normal, well educated, well-adjusted people.
IOW, you are ruining their delusion, and they hate you for it. They are convinced that what they are doing is important, substantive, and deeply profound, and given the profundity of their cause, they, in their paranoid view of reality, are convinced that "evil forces" are "conspiring" to thwart them.
They are convinced that YOU are the manifestation of their imaginary conspiracy, and that you are sending out secret messages embedded in your "placemarker" posts, coordinating with other conspirators who are out to thwart and "torment" them. This is the twisted thinking of the paranoid mind.
That is why they stalk you, attack you, and accuse you of the very things that they themselves are doing, transferring their guilt to an external person, thereby giving themselves the absolution they so desperately seek for the compulsive actions the are unable to resist.
*the phrase "the ignorant lunatic fringe element" does NOT refer to all people on these threads who reject biological Evolution. It refers to a very small minority, who exhibit bizarre characteristics in their posts, who would, among their many other bizarre undertakings, create out of whole-cloth the delusion that PH is actively attempting to disrupt the discussion, "get threads pulled," etc., ad nauseum. It refers to certain anti-Evo Freepers of whom even thoughful Creationists are getting sick and tired.