Because of powercreep you can defeat a boss in EW and never see half of the mechanics.

Take Nald'Thal. The scales, You may never see it anymore because he dies too fast, let alone all of the "Underworld" stuff he does with switching colors and heads. And this is not to mention the remainder of the game. So many trials, raids, and dungeons, are just complete push overs form older content.
Take A9, The Refurbisher. It routinely kills folks because no one knows the mechanics, but also dies just after Full-Metal Faust is defeated. Cruise Chaser skips entire phases and will go straight into Eternal Darkness easily. Alexander Prime can die before or just as it casts "Summon Alexander", doing Time stop once or twice.

The content is completely trivialized, you can fail mechanics several times in a row, and never die. You almost have to TRY to fail, so if someone does fail, its always "this guy must be trolling".

"Go do Savage". What a lame answer. I do Savage and it sucks. Partner up, Spread, Light Party Stacks, Raid Wide, Tank Swap. The entire experience is so rigid, planned, scripted, whatever you want to call it. With the number of body checks in savage force you to restart time and time again after small mistakes. I've seen many people refer to it this way, its like playing Dance Dance Revolution. Savage isn't hard as much as its tedious. What will you say next? Go do Ultimates? What then?

The two-minute meta is the end result of homogenization and lazy design/balancing. And should honestly just have a whole essay about by itself. Its a culmination of several different factors that I could go on literally forever.

The TOS is a problem. And without trying to sound like a certain someone who frequents the forums, they do not enforce their "3rd party tools are cheating" bit. They, however, will take action if you are even just a little frustrated or in disagreement. I've had a friend who just started the game after EW released. In Sastasha, he was only single pulling and a DPS told him to pull everything. He said he wasn't going to. He was reported and had to talk to a GM shortly after. He tried the game and at the first disagreement someone had with him, his first interaction with another player, and he got a strike on his account. He has not played since.