The results aren't pretty...
This is something that existed prior to ascended gear, and was something that we saw happen all the time in GW1, even without any sort of gear progression. Some players, typically people who play the game a lot, tend to only want to play with other players that play like them. They require some sort of proof to get into their party, whether it be displaying your Lightbringer Title, equipping or linking some type of gear, or using some other method of showing that you have already done and are experienced with the content. While ascended gear might be the new excuse, this behavior happens regardless.
While this is not really something that we want to encourage, players do have the choice to play the game in the way they want. We can’t force those players to be all-inclusive in who they invite to the parties they create, and to be honest, doing so would probably make people even more unhappy than they are now, and lead to a lot of undesirable behavior.
tldr; people are going to do this anyway, we dont't want to encourage it, but we can't control how people react to content.
The Agony mechanic wasn’t introduced at the start of the dungeon so that everybody can experience the content. While one of the goals of the Fractals of the Mists dungeon was to provide some difficult content for players looking for a challenge, we also wanted the dungeon to be available for everybody to experience. While getting far into the dungeon requires agony resistance from ascended gear, the content was designed to provide challenging content, and to allow players to choose what difficulty they wanted to play at.
As for ascended gear, to reiterate what Chris has said (https://forum-en.gui...Chris-Whiteside), it’s not intended as a treadmill, but rather as a tier of rewards that can help bridge the gap between Exotics (a few hours of effort to acquire a piece) and Legendaries (hundreds of hours of effort to acquire one). They’re currently only available in the Fractals of the Mist Dungeon, but we’re going to be adding new ways to acquire them, both inside of WvW as well as elsewhere in PvE.
tldr; we want everyone to experience content... Now watch as I reference Whiteside's post without telling you why Ascended gear needed to have more stats than Exotic/Current Legendaries, and tell you there is no gear treadmill...