FATEs
While the dungeons/hests/trials provide a great learning curve to anyone new to MMOs, sadly, they are mostly optional. At launch, FATEing was very feasible and it allowed people to reach level cap without learning a lick about playing their class correctly. FATEs are not as viable to level with now, but the problem still remains. It is evident in low level dungeons where people fail at basic things like dodging Landslide on Normal Titan or removing Doom from Temple of Sarn's first boss. Instead of teaching new players how to remove Doom, I see things like "stand on the hill to ignore the mechanic".
Commendations
The commendation system just promotes people to stay quiet in runs. If you criticize someone's play, there goes your commendation. Even if someone can obviously improve their rotation and shorten run times, most of the time they simply do not care what others have to say about their playstyle. I've seen too many BLM who insist on staying full MP or Bards who think their DOTs are not worth using. Even times where I point out that someone can improve themselves, I get responses like "Don't worry about how others play" (edit: and no, I'm not a huge jerkface about it, I'm usually quite calm and clear about things). The commendation system is a waste right now, because instead of teaching new players how to improve, it is a simple "say hi in the beginning and then stay quiet for whole run" thing instead. (Or just spam guildhest until you get your mount).
Duty Roulette
Instead of using low level dungeon/trials as a place to learn, you simply get teamed up with players with multiple 50s and full gear on. This skews their perception of the game and really does no one any favors. Low level duty roulette is primarily Sastasha <-> Halatali. You rarely get a dungeon above that and when you do there is a good chance of failure. The guildhests are simply being farmed for Commendations by geared players, and in turn the new players learn very little or nothing.
Exploits
Pulling Chimera up the hill pretty much negates the entire difficulty of the fight. Allowing players to ignore all abilities in Turn 2 ADS is a step in the wrong direction. You have a crowd of players who need to cheat their way through the game before reaching walls like Titan HM/XM, and then they get frustrated and quit, blaming things like 'latency' instead of personal error. Or, they'll resort to buying runs from good players and in turn never improve themselves.
So the next time you come across an awful player in the endgame, think about these factors. Yes, bad players exist in every game, but the fact is that this game will constantly reward you for being mediocre. Echo buff even allows bad players to finish quests that normally would require class rotation knowledge. People don't want to improve and instead demand the game gets nerfed down to their level. WP/AK were great instances before. Now they are a joke. I'd hate to see all the other dungeons reduced to such triviality.
edit: 1000 character limit