As the title suggests, elitism has been on the rise and I think the current implementation of accessibility has played a significant part in it.
People are prone to us or them thinking. If you think you're not, then you're an idiot. In the absence of a clear us or them, we will create one, somehow. For evidence, read any history book.
WoW used to have some clear us or them divides. Raiders and non-raiders were distinct. Either you could raid and did or you couldn't and didn't, or you didn't want to and didn't. But there were clear portions of the population which were able to be defined as non-raiders. Then there were raiders, who again could be divided up. If you were in Naxx or AQ40, you were high up there. Guilds in the BWL range were of some significance, though that category could be broken down quite a bit based on which bosses were killed, since some were very clear barriers to progression and could keep a guild busy for literally months. Then there were the swarms of MC guilds in various stages. And non-raiding guilds. PvP guilds too. Lots of those.
This is a much different 'society' than the current WoW in which a much larger portion of the population raids. But more importantly: they all raid the same content. There used to be tiered progression; now we have the latest tier and all the other stuff. Unless it's the weekly, Naxxramas is about as relevant as Molten Core and Ulduar is a place to get mounts, not much better than Tempest Keep or Karazhan.
The us and them is much less clear, but humans will be damned if they cannot find one! So, we find ways to divide ourselves. We didn't always have to search for differences. The structure of WoW provided them for us.
The tiered progression system meant that different players did different content. This has two results. First, it means players are 'physically' separated. The highest tier raider isn't running the same content as the new warlock in greens who hasn't quite figured out that fear is dangerous to use in instances. They might meet in a BG or farming, but there will rarely be situations in which the warlock and, let's say mage, are in the same group. Ubermage does Naxxramas and a few lower raids for his gear, all guild runs. Nublock runs Scholomance and Blackrock Depths; maybe with PUGs, maybe with a low-tier guild. His DPS sucks and he might not quite know what he's doing, but he'll learn eventually, because he has to. Ubermage isn't there to carry him. Ubermage also isn't there to flame him.
It was in this environment that I learned. I didn't get a lot of help. I didn't get a lot of grief either. I was either with other noobs or with alts of higher up players who knew exactly how awesome they were and had no need to put others down. Sure there were the bragging types, but they pulled themselves up rather than pushed those around them down. Their rising tide didn't sink our boats.
Players did content which suited both their gear and their interests. No one was facerolling Stratholme, since by the time they could faceroll Stratholme, they had absolutely no need for loot from there. Besides, screwing up a gargoyle pull was still trouble, so even at high gear levels faceroll wasn't the solution to all problems as it is now. This meant that players learned. It also meant that they developed some level of respect for people in that content, since they tended to experience it when it was hard, as opposed to now where the majority of our experience with an instance is in a trivial form, so anyone who has difficulty with that instance looks terrible.
Raids in general have gotten easier. Much easier. Oh but what about hardmodes huh? I've not killed Arthas hardmode have I? Nope. But that's part of my annoyance with the current raiding system. Raids used to be of moderate difficulty in the gear they were tuned for and due to progression one couldn't easily outgear a raid that they hadn't already cleared. Full blues were somewhat impressive, and oh man, if you were so lucky as to have someone in your raid in epics, awe-inspiring. I'm exaggerating. Slightly. What I'm trying to get at is that raids used to be somewhere in the middle for difficulty. Some fights were harder than others, such as a basic tank and spank like Golemagg compared to the CC-intensive fights like Garr or Majordomo Executus or positioning fights like Baron or Shazzrah. Or was it Gehennas? They look the same. The guy with arcane explosion, teleport, and oh my god quit using fucking dots! Now there's easymode and hardmode. Trivial success or insurmountable failure. It doesn't help that they take place in the same instance, with the same boss, and many of the same mechanics. Great progression there.
So here's what it all adds up to: players are not different anymore. We all wear the same gear, run the same raid, faceroll the same mindless randoms. Even our alts all look the same with 80 levels of the same heirloom shoulders, chest, and weapons. There's no clear us or them. So we make one. We obsess over DPS meters. We go after every gem, every talent point, every glyph. We ask why, why are you not doing your research? And when they say they don't care we call them lazy. Because dammit, we are going to be different from them and if we can't find them we'll just make them up.