I would here propose that we are discussing the issue from a wrong agle.
Elitism at it's core is accepting only the "chosen" into your company. It's the attitude that "If they don't measure up to my standards, I won't play with them." This limiting of your acceptance, of the company you keep, is the core of the term. Also, ss such it is not a binary state of "I'm elitist or I'm not elitist", but rather "How elitist is one". The degree of elitism is the issue.
But the real issue is "How does elitism affect the game". This is the crux of the issue. Some elements of a lithmus test for this that I'd consider are:
-is most content done in a specific way that players find restrictive? Do you by now need to have a specific build to be allowed into a group? Can you still explore the dungeon, or must you take a specific path that avoids monster X?
-is it hard for someone to find a group that wants to do content the non-standard or casual way? Is it hard to find a group that will actually fight Kohler? Is it hard to find a group that would like to try to actually defend Magg by fighting? Is it hard to find a group that will do a full dungeon clear?
-is the speed at which the elite are accomplishing things leaving others behind? Are a casual player's earnings from casual play still allowing him to meaningfully participate in the economy? Is a player with multiple characters disadvantaged to the point where he cannot keep them all geared up enough to keep getting into groups?
-is there a social stigma for not measuring up? Does a casual player listening to the map chat find himself realizing he is considered a scrub? Does wearing non-elite skinned armor mean a player is not respected? Not taken seriously?
At the OP: elitist rejects the lvl 25 in AC because he doesn't measure up to his standards, because he's "not good enough". A non-elitist rejects the lvl 25 in AC because he believes everyone should be treated equal and has to pull his load.