There aren't as many veteran players as you think, nor former retail players. At least not on Deathwing/Ragnaros, where a large part of the population (if not the majority) are kids with poor English and cognitive skills who can't (sometimes even refuse to) learn fight mechanics or how to play their class.
ToC 10/25 is a special case, it can be difficult even for vastly overgeared raids when half of the raid refuses to move from poison pools. I remember trying to start a ToC 10n, requiring "only" around 4,5k gs - for almost an hour I couldn't find a single decent tank who would know how to tank ToC 10 or at least speak English to be taught tactics.
Then there's a case when someone at 3,5k starts a ToC 10n, demanding 5k gs min. Or 5,8k + LK achievement for a ICC 10n pug. People love to be carried.
Yesterday I saw a 5k gs ret paladin using Seal of Light to dps throughout Forge of Souls, ignoring any advice, and later a 6k gs DK, specced as frost DPS, who hasn't used a single frost ability except Icy Touch throughout Pit of Saron run. And these are far from exceptions.
No wonder that with such a player base people either demand ridiculous gearscore values to ensure their raid's success, or genuinely believe that ToC 10n is impossible to complete under 5k gs.
Experienced and veteran players have decent guilds to run with, the rest struggle with pugs. On the other hand, it's not easy to find a decent (!) guild that doesn't require recruits to be already geared for ICC/RS heroics.