I don't think it's quite that simple. Things don't just "fall into place" for all of the reasons I mentioned in the article. The dynamics of the game are such that to progress in a large guild, some of your quicker-advancing members will eventually hit a wall where they're doing content they no longer need for months to help the lesser geared characters progress.

Since there's no stigma for just hopping over that wall (by switching to a more advanced guild), it's a powerful temptation even for the most dedicated guild members. If your guild was formed largely around loot acquisition (as most raiding guilds in WoW are), you're probably going to choose to continue advancing your character somewhere else as opposed to a lootless raid grind of indeterminate length.