^^^That's exactly what's going on in Lordaeron. There are a couple of LoD guilds than only recruit one 6.2+ person every blue moon and on the other hand there are social guilds, with hundreds of players, and maybe an aim 5 ICC core stuck on that for months, which never progresses because players are always leaving for another guild, or just get frustrated and stop playing altogether.
There's just no way for new people (new as to new to wow or wotlk in general) to gear up or join a good raiding guild. Most have to grind for months for a couple of items, then move onto another guild that has a bit more aim, and repeat that cycle until they can enter a guild that does all content, taking into account that most lowbie guilds are full of ninjas, always disbanding or riddled with drama.
That's why most of the top raiding guild are full of alts of other top guilds, I personally know a guy who raids with 5 of his chars in all of those top guilds, basically all those guilds are the same group of people. These guilds are very hermetic and you have to jump through a lot of hoops to get into one of those without a recommendation. The grind and filters that once has to pass in the span of several months to get into a hardcore 12/12 8hc guild is too much for the majority of new players, and that splits Lordaeron into some monolithic "pro" guilds and a dozen churning, always changing, guilds that can't kill festergut or DBS hc before they disband and reform into a new one riddled with the same problems as before.
The only thing keeping Lordaeron alive is that people spend so much time grinding gear here that they are reluctant to leave after so much time. But if someone puts the numbers of people joining and how many of those actually reach Kingslayer or LoD, the number is abysmal. There should be a better way for players to gear up, do more bosses and actually progress on the server. People want to have fun, kill bosses, high-five Arthas. Not play for a year without seeing BQL.