I didn’t like the rule when it was proposed. Back when we had threading in vBulletin I didn’t think it served a purpose, since you could turn on threaded mode and hijacks were no longer a problem.
We don’t have threaded mode any more, which is unfortunate, so I guess it is a little helpful now. But I still think it’s not worthwhile.
My preferred interpretation of the rule is and has been, OP must present a focused question for debate, on-topic posts should relate to main arguments addressing the question and direct counterarguments. If a side conversation is likely to or has shifted the discussion away from main arguments addressing the OP, it’s a hijack.
This obviously doesn’t always work for P&E. For example there are breaking news threads in P&E and there are threads covering the whole of a major investigation or the whole of a candidate’s campaign for office. I mean, there’s a single thread for the entire term of each British prime minister. Could you imagine if we had a single thread for the entire Trump administration? We had one thread for the entire Boris Johnson administration. I often struggle to understand what is or isn’t on-topic in P&E.
As for how I follow the hijack rule in practice, I keep in mind an early precedent:
~Max