Why do so many posters have trouble staying on topic?

I’ll point you to the specific moderation for the split in the Iran thread which had already had a ton of extremely off topic posts and long segues of Trump bashing.

In a perfect world, the original thread would have been breaking news with a follow along P&E thread, as is most frequently the case. Posters chose not too, and so all the discussion was in the P&E thread - no real, workable way to put the genie back in the bottle.

Thus, as stated in the link above:

The current thread is to discuss actual actions being taken. It’s not a Breaking News thread, but let’s keep the discussion confined to what is actually happening and the immediate, direct repercussions.

Therefore, an effort to try to make a Breaking-News-style P&E thread. It was a kludge, but note the many, Many hijacks that had occurred long before we tried to fix it. Given that Speculation was normally not allowed in a Breaking News thread, we split off past and future to explicitly allow freedom of speculation.

Was it a perfect fix? Apparently not. Was it well received at the time we rolled it out:

Yes, pretty much! But with perfect 20/20 hindsight, we could probably done better. If I had a time machine and all… well, perfect knowledge from the future would fix a LOT of problems, no?

So, and back to the Present, we’ve rolled out the HT option, which also will not be a perfect fix but it’s another option.