Because locals always tolerate tiny mistakes. Let's say a new user registered today and copy-pasted some random article in our local thread, in the past days, we were used to asking him to edit it and add the source or delete it. Do you see the tolerance here? Global members would go ahead and report their posts and they would get banned without having a single chance.
We have tolerated many more things in our local thread and that is the reason they were able to abuse every single feature of this forum. Someone has to stand up against them, and I thought it was the perfect time to step up. Luckily it worked and they stopped doing what they were doing for a while.
Maybe it is the case with your local board. I would not say that is a common thing for every local. For example, in russian local, where I constantly write, the situation is different. Sure, the members there show support and give reasonable advice, but you also come across lots of sarcasm and irony, even intolerance sometimes. I am sure most of local members would not hesitate to report some newbie who is violating forum rules.