Lots of people have lots of ideas on what is to blame for the touted death of the PUG community. Fresh in my mind since I just listened to the respective episodes are the Multiverse gang, who blame Gearscore, Deadly Boss Mods, and other addons in their latest episode, and Klepsacovic's appearance on the Twisted Nether Podcast, where he points the finger at cross server groups, amongst others. I feel that this is blaming the tools for the actions of the tool users.
Many major MMO's, including WoW, EQ2, and Rift, now offer tokens good for high quality gear rewards as an incentive to keep players running instances that they no longer need. This is the exact opposite of what happens everywhere else in MMO's - both solo and raid content eventually all but stop rewarding players who have farmed them into the ground. Instead, non-raid group content is pushed into an odd situation that Rohan discusses in which the participants have markedly different goals.
(Ironically, Rohan's post responds to another post of Kleps', completing the bloggy circle of life.)
If the only reason why players are continuing to run this content is to gain the rewards, it stands to reason that they will want to do so as quickly as possible. If they don't need to use crowd control or tolerate newbies, they won't, because they're not being "paid" to do so, just for completing the dungeon. This is not the dungeon finder's fault, or gearscore's, and would happen even if these things were removed from the game.
As Rohan says, the real problem is the daily dungeon quest bribe, which exists because developers have yet to come up with a better way of making sure that late-comers still have people to group with for the entry level content. The problem only gets worse in an endless cycle of vertical expansion Tipa terms "the Expansion Trap", and that I've been griping about on and off for a while now. The further upwards progression climbs, the more damage to the existing game will be needed to get newbies up to the level they need to reach.
Blaming the tools for this is like suing the hammer manufacturer for your broken window when turns out that someone picked up the hammer and broke the window so they could dive into your house for cover because the management was shooting indiscriminately into the street.