The issues are many, the first is iL. Most high level players believe their iL will carry them in older content, forgetting that if your level is capped so to is your gear. Then there's the nature of Duty Finder. You don't know who you're being teamed, yet most high level players seem to think that new players don't exist anymore and that everyone they're running the content with is also moonlighting for Roulette rewards. They also believe that you have access to more abilities than what the level range would allow. This is most prevalent among those who haven't actually leveled the class in question. Then there's the notion of who sets the party's pace. Most have this idea that the tank sets the pace no matter what the content is. This is a blatant lie that's somehow become 'truth', tanks may pull in this game but if the healer can't heal you through all the damage of a large pull or the DDs kill them in a timely manner then you're not doing large pulls. The party sets pace.