Actually we have seen two recent sucessfull interventions:
(1) The "no edition wars" around the time of the 4e launch. This kept the worst of the edition warriors from each others throats for a while, and allowed discussion on more useful areas to flourish.
(2) PDF/WotC is teh suxxorz threads moved to the sewer. Pulling all those threads into a temp forum allowed them to be moderated more easily, and made them "out of sight, out of mind" for many.
There has been a number of comments on a number of forums that the "edition wars" are back - it strikes me as perfectly reasonable that the volunteer moderators of a site like ENWorld choose to temporarily restrict some contentious topics for a limited period.
As I think has been said by the mods: they're here to keep the peace - so if they think that their job would be made easier by this, then fine. And hey - PCat may be changing his mind on this one!
You know, people keep comparing the 5E threads to edition wars and such, but I am not really seeing it. There were only really a handful of them for a few days, and of all the different ones I read, none seemed particularly full of flames or hurt feelings. The various threads about the Forgotten Realms and Elminster were far more full of flames and hot tempers, and the 5E threads were fairly civil.
The truth is, while people here are arguing that 5E threads are doomed to failure and edition warring, I think the actual threads prove that it is not the case. Sure, there may be one or two mean-spirited posts, but that is the case no matter what is the subject of discussion, and nothing about the topic itself seemed to actually aggravate it.
Comparing this to the threads discussing 4E after the original 4E announcement and close to the 4E launch is flawed, I think, simply because the situation is totally different. Those discussions were talking about a new edition that was concrete and real, and was clearly going to be something that some people didn't exactly want. 5E, though, is little more than a dream, and it little more than a name to give to what people want to see in an "ideal edition". After all, what we talk about in those threads doesn't have to resemble the eventual 5E in order to be relevant.
Overall, I think I would be happier if the ban was merely on speculation regarding what WotC would do with 5E, rather than the discussion of what people want to see in 5E or what would work in 5E. If that makes any sense...
On a side note, I'm getting a little annoyed at all the people equating the discussion of 5E with people who hate 4E. I love 4E, and prefer it to all previous editions, but I really enjoy talking about the future of the game and the ways in which the game could be improved even further. You don't need to hate the current edition in order to want to see a better new edition.