Repetition has a place in the world; there are long established family jokes and references, nursery rhymes and songs in general, soothing sick people and summarising what has been said so far, for a start. So don't assume I am simply opposed to repetition.

But I have three main problems with Repetition in threads.
The first is that the poster does not appear to be listening to what other people say.(Normally they claim others in the thread aren't listening to them, which is often true but doesn't invalidate the observation.) In The Monstrous Thread referred to above I looked at the last 50 posts - that's my preferred approach an long threads - a day or two before I was out of the country for three weeks with very limited Internet.   When I came back I was surprised to see the thread still on the go.so looked at the last 50 posts again. And as far as I could remember it had not progressed in the slightest; same people, same specific events being argued about. Just a roomful of people all not listening to each other.

The second is like the first: there is so much ego in the postings that they assume they are the only ones who can see a flaw in an argument. If I happen to say something imcorrect to someone, it isn't always necessary for then to point it out. Allow for the intelligence of the other readers; most of the time it will be as obvious to them as is it to you. That's why I try to stick to the post-clarify-shutup model for any given point.

But the third reason is the most important. The world is full of wonder and people are marvellously complex. I hate reducing people to 'the one who is obsessed with X'. The more energy people pour into narrow topics the more they reduce themselves. For illustration I pick Teribus at random. I know his political stance so well I can predict how he will react on any remotely political topic. Buy beyond that? I know nothing of the guy. What sort of music does he like? No idea. Does he play an instrument and if so what? Pass. As seen through the posts this fully fledged real and complex person with live and interests is reduced to a single note. And that is not gooď.