Oh man, where to begin.
A few of my favorites that I've seen in the past:
- Moving the goalposts of what it means for criticism to be constructive. For example, Player A mentions something they don't like and they propose an idea on how to fix or change something. Player B: "No your criticism isn't constructive because I disagree with it."
- An overall lack of verbal reasoning from some members of the forums. Someone reads a post and misinterprets the meaning and/or tone of the post which leads to that person creating a strawman argument.
- Ad hominem attacks in the form of foul or passive-aggressive language. I usually saw this when forum members were discussing flaws of the Endwalker MSQ. Someone would jump in the conversation and curse people out or say something snarky/patronizing.
- Appeal to tradition: "This is right and shouldn't change because the game has always been like this."
- Inconsistent arguments. Someone presents an argument but you remember that same person was arguing from the opposite position just a week ago, which can be confirmed by looking at their post history.
- False dilemmas. "Oh, you dislike how the story writers went in this direction? What are you saying? That the writers should've done this instead?" Some people just don't realize there can be more nuanced solutions.
- Circular reasoning.
- False premises.
- Red herrings. Usually done when a forum member doesn't have any more useful data to back up their claims.
- Non sequitur fallacies.
- Appeal to ridicule.
- Double standard - I usually see this in the form of "negative feedback of FFXIV is just an opinion but positive feedback is a fact."
- Appeal to emotion - Emotional arguments leveraged by some members of the forums. I.E. "Providing negative feedback can hurt the devs' feelings and is equivalent to harassing the devs," even when the feedback is delivered in a pleasant or neutral tone.
- Impostor fallacy and Traitorous critic fallacy - Usually seen when an FF player is criticizing or providing negative feedback of FFXIV, and other forum members accuse the player of being a wow shill.
- Just because fallacy - Forum member provides no proof of their claims. I.E. "trust me, bro."
- Logic chopping - Forum members when they try to split hairs over the definition of a word.
- Slippery slope - I saw this back in Heavensward before dueling was added. Some forum members believed adding 1v1 dueling to the game would lead to an overwhelmingly toxic pvp-focused game.
- Argument by gibberish - Also used by forum members who have no more data to back up their claims.
- Moralistic fallacy - Venat sundering the ancients.
- Appeal to false authority - Used by Yoshi p when he says the cash shop is controlled by the "scary baroness lady" and he has no control over cash shop prices.