I blame a large part of this type of mentality the OP describes on the way the community has flocked to YouTube videos and guides as a way to "train up" to clear content. It's created this atmosphere where everyone is impatient and unwilling to learn to overcome a challenge as a group and build camaraderie.

The community for the most part is really toxic and rude, and in my experience a lot of the rudest, most toxic players are also really really bad at the game to boot, but love to point out others mistakes.

I enjoy the game and the content the developers provide us but I only experience it with my static raid group... Venturing out into party finders and duty finders is not worth the hassle because people are rude and self righteous. I really feel for people that haven't found a group of people to run with and are forced to deal with the issues I see in party finder and duty finder.