Some points:
AP isn't the be-all, end-all of knowledge and there will be exceptions, but chances are the person with 10k AP knows their class a lot better than the person with 600 AP.
Even in dedicated speed run guilds, people may not be able to form a full guild party. If 18 people in a guild want to run dungeons at the exact same time, one or two groups will either have to run incomplete parties or pick up a pug.
LFG is filled with all sorts of posts, ranging from "newbie looking for guidance" to "10K AP ZERK PING GEAR OR KICK". If you're a casual, don't join the zerk group and then cry because you got kicked for not knowing what to do. If you're a zerker, don't join the group you deem subpar and then rage because you think they're clueless noobs.
It's silly to compare the state of the game in September of 2012 to the state of the game in 2015. No one had AP so of course it wasn't used as a measurement (however poor) of experience. Furthermore, most people were still rolling around in blues and greens, struggling to get through AC p3. Now that some people have figured shit out, why should they not be allowed to look for others who want to play in a similar manner?
If you think that "fixing these mechanics" will get rid of elitism, you're out of your mind. Even if ANet somehow completely nerfed zerkers beyond all repair and made party healing and condition-spam absolutely necessary, people will still find the most optimal builds and optimal ways of clearing content and will want to do said content with like-minded players.
tl;dr: Yes, there are elitist assholes out there, but railing against all zerkers and wanting to deny them their parties is no less toxic a mindset. Find the group that suits you and quit trying to make everyone else play your way. (And FFS, I don't care what side of the fence you're on, please refrain from harassing other players.)