I'm 90% sure this is a skill issue, not CP issue. High CP is ofcourse very powerful and helps alot, but i'm sure a cp2000 tank that only puts on 300 of them will still be much better than my cp2000 DD that rerolls to tank.
The typical beginner tank will block EVERYTHING because they don't know what is safe to soak and what oneshots you, then they run out of stamina and dies. Practise is needed to learn resource management and experience is needed to learn how to deal with every attack in the game (dodge/block/eat), because a red cone on you can be everything from tickling you to oneshot.
And there lies one of my biggest issues with the game, the lack of opportunity to practise tanking. You can't level in tank build with questing since tanks do zero damage. If you sign for a normal dungeon you probably get vote kicked for slowing the group down. Even in veteran dungeons the group kills a pack faster than you can taunt half of it. And then you enter veteran DLC dungeon without the practise and experince required and you are not skilled enough for the job...
/Sad frustrations from relatively good WoW main tank.