Because even if his/her absurd blatherings don't convince anyone here, it's very annoying to wade through them and lots of readers will simply quit reading the thread. It's one way to hijack a thread that threatens an agenda and we've all seen it done before on many subjects.
Those who have read all the way through may get some amount of new information that will make a difference. Who knows how many readers left this thread in disgust.
That is a VERY good point. The trolls annoy me, even though I understand where they’re coming from and know to ignore most of them anyway. If I were just dropping in on the thread in search of info, they might well cause me to leave in disgust. For the life of me, I don’t know why they’re given such latitude on Eligibility threads. They wouldn’t get away with half this stuff on regular FR threads.