I was reading Liore's post, a response to the posts of two other bloggers, about gatekeeping in MMOs, and I found myself pondering. The issue is that gaming is leisure time, and thus we want to ensure we have fun, which for most of us means success or at least a feeling of progress. In a game involving multiple people that means ensuring that each person in our group is as dedicated and skilled as we are.
Because ensuring fun during this time is so vital, it makes us a risk averse. We want to control everything we possibly can to ensure that it goes well. That is what drives us to sites like Icy Veins to seek the best builds, it's what drives us to keep gear gemmed and enchanted despite knowing full well that it will be replaced soon. That same risk aversion means we don't want to have faith that the person in poorer quality gear is at the same skill level we are. We want to take the people with better gear because it tells us that at least this person has seen the fights and handled them. It means that at least one other group thought they were good enough. Now having the gear doesn't necessarily prove anything; they could have been carried through, but it is the strongest indicator we have.
I should add, while I see why PuGs do it, I think its terrible for long-term guilds, where, like in hiring in the real world, you are looking for the person that fits your team, not necessarily the person with the best resume. But in a PuG you don't get that chance at an interview, you only get that resume in the form of their gear and achievements. If your group's success or failure is going to be reliant in part on this person you don't want to take any chances. So when the decision is short-term you take the safest route.
I digress; in the posts Liore responds to they suggested things like an "effort gearscore" or mandatory version of proving grounds, and I agree with her when I say that I do not think they will work. All they attempt to do is automate the process of selection, but WoW has already tried to do that with mixed success. Plus, the community will always want higher standards, and Blizzard will always want lower (because they don't want people to not play their game, they want accessibility). If we institute a "gear score" or even "effort score" for a boss, people will expect it be higher in their own groups. If we institute the requirement of a silver medal in proving grounds, guilds will want gold. No one wants someone who "meets expectations," they want the best they can get.
So even players who meet these automated requirements are not necessarily going to get into raids; all it does is thin the ranks and add barriers to entry, and by now I think its clear that those are things Blizzard wants to avoid.
Unfortunately, when it comes to leisure time, people aren't likely to change their attitude any time soon. For guilds, they'll forever need to take risks on people, but I do not think making things more exclusive is the answer. Sometimes the right player just needs a little tutoring.