I started both a fresh MRD and GLD for 3.2 and did not have problems.

When playing as a DPS, some tanks held threat, many didn't. When playing as a DPS with an experienced tank buddy of mine who started a new tank, there was no problem.

I'll go as far as saying tanks have the highest entry-lvl learning curve, but it's not as if the game's math doesn't allow you to keep threat. Well, so long as you keep your gear up to date, but that's on you.

To be fair, in many ways the game is new tank friendly. As fresh low-level tank, you could get hit by every avoidable AoE, not hold threat the entire dungeon, and your group is still likely to complete the duty without wiping.