That's not the problem. The problem comes when an asshole has a list of ten or twenty "fallacies" in his notepad and instead of talking or discussing the issue being discussed in a thread with at least some minimum sense of politeness, charity and modicum, goes on derailing the discussion into one of a metadiscussion of this kind, "this is a fallacy, that one is too, you are too dumb to even realise it", etc.
This kind of tone trolling is hard to fight, because "in the books" seems fine. It's about getting the fallacies out of the discussion, it's about throwing out the "stupidity" out of the discussion, so that in "theory" all that remains is pure, intelligent and non-fallacious. What it actually ends up happening is something akin to (for instance) the Pharyngula comments section, where absolute bullies roam the threads looking for any newbie for them to **** up with, "refute" and "shown" how utterly stupid and mindblowing idiotic their little brains are and some such, for they are the harbingers of logic, reason and fallacy-destruction.
This shouldn't be a surprise to anyone. People are people, and to prevent this kind of corruption and degeneration we need much more than "rules", be them logical or some ****. We need people to understand they are addressing other people, to understand this basic humanism even in simple endeavours like "discussing things in a random internet forum" and that the really hard thing to try to do is not to be a dick to them, despite any shenanigans you might find them doing.
I really like these kinds of rules, but they should always be seen (IMO) as a self-learning thing, not as an enforcement for discussion.