Rather than have a split system of inclusive and exclusive content (which was exactly the model used in Vanilla and BC) you have tiers of difficulty with rewards located on each depending on where you want to go and what you want to do. That way, everyone gets to see/exp the content but nobody gets excluded.

Currently in FFXIV, content is exclusive. The problem is that the entire endgame is exclusive. The Ifrit HM fight is accessible enough, Garuda is just barely (b/c it's halfway a dps check as well) and Titan is exclusive (therefore you cannot get relic w/o a competent group). Binding Coil of Bahamut is also exclusive due to the Titan check as well as lockout and not being on the DF.