There's a skill gap and there's an experience gap. I think a lot of people tend to confuse the two (especially here), and that the skill gap isn't nearly as wide as most people think.

The experience gap is caused by impatient players who can't be bothered to teach others how to get through content, and who leave at the first sign of trouble. This causes a situation where PF is filled with parties that require experience to get in. This leads to a situation where the only way to get experience is to have experience, which leaves new players who don't have connections in the dust.

I do think the skill gap is fed by the experience gap, and that the perception of the skill gap is amplified by it as well. People see others fail to mechanics they failed to explain (but that were explained to them only after they themselves failed), and assume the person who failed is bad--when in fact, they just didn't know what to look for. Many people also forget that raid awareness is a learned and practiced skill, and that we were all n00bz at one point.