The fastest way for a discussion to degenerate into uselessness is for each side to convince themselves that the disagreement stems from the other side being stupid. If you assume that you understand someone else's point of view, and that the disagreement is occurring only because they do not understand your, clearly superior, point of view, then you aren't going to get very far1.
Of course, one of the challenges is that people rarely actually articulate the reasons why they are doing something, and often aren't completely aware of the reasons themselves. People rationalize and then argue against the words used to express the other party's rationalizations. It's some pretty fantastically unproductive stuff. It certainly doesn't get any easier when one side never even presents a point of view at all.
People who start raids in trade chat requesting that everyone who comes have a certain GearScore rarely get drawn into the debate about whether GearScore is a useful tool or not. Other people have that debate for them. The arguments against are generally that skill is far more important than gear. The arguments for are generally that since there is no readily available way to measure skill, gear is the best we can do2.
But those arguments actually don't have much to do with the problem or with either side's motivation. Whether or not GearScore is objectively a useful tool for forming successful raids doesn't make a huge difference. The group that doesn't like GearScore doesn't like what relying on GearScore does to the game and to the community. The group that uses GearScore doesn't think that the GearScore haters understand the reality of forming PUG raids.
I completely agree with the GearScore haters and the majority of the WoW blogging community who say that using GearScore to form raids have a negative impact on the game. For me, though, this has nothing to do with the fact that GearScore can't measure skill, and it has a lot more to do with the fact that GearScore can't measure willingness to learn, ability to take direction, social skills, dedication, and any of the other traits that would make someone who has neither gear nor experience a good addition to a raid. The problem with GearScore isn't that it shuts out people who somehow deserve to be on raids, it's that it shuts out people who just want a chance to play and learn.
It's also worth noting that GearScore can't measure whether or not you are just a complete asshole. When it serves as the only entrance criterion it basically gives people a pass on destructive behaviours and attitudes.
For a trade chat raid leader, though, giving people a chance doesn't seem like a viable option. The reality of PUG raids is very harsh. We all know that a PUG raid can break up after a single wipe at worst, and that for something like Vault of Archavon the lifespan of the raid is half an hour to forty-five minutes maximum even if people are willing to stick it out and try again. A leader under these circumstances doesn't feel like they have any room to give new people a chance.
It's also very questionable whether giving new people a chance is very beneficial in this kind of scenario. No one explains the encounter before it begins. There is no discussion of what went wrong if things do go wrong. The closest thing you are likely to get to constructive advice is being called a "n00b."
The functioning of PUG raids in the current environment seems antithetical to the idea of giving new people a chance to play, to learn and to prove themselves. Despite the attention that GearScore gets, then, it is only a symptom, not the cause, of the problem. The real problem is one that people on both sides of the debate are caught in.
While ultimately if we can solve this problem GearScore may lose its place as a tool of choice for selecting raid membership. But banning or breaking the addon doesn't do anything to the underlying problem that PUG raids are the most obvious avenue for new and casual players to experience raiding and are simultaneously the worst possible environmental for new and casual players to experience raiding.
1. Unless you are in a situation that are are capable of outright winning. When the entire problem has to do with opinions and social interactions it is very rare that this is an option.
2. Of course the arguments are often a lot closer to, "You asshole, you are ruining not only WoW, but life as well!" versus "Noob!" with one side or the other quickly resorting to, "You are a virgin who lives in your mom's basement." This is trade chat afterall.