Honestly, this is probably exactly the reason right here. The problem with Savage content is not that it is hard on the Tank. The problem is finding 7 other players who are not pants on head stupid and fail at the mechs/Dps checks. This is not a new problem. It's been around forever.
If we're looking at mechs, though, then there is a difference. By comparison, the Mechs of Savage Alexander are substantially simpler than ... well, almost all of the Coils (T3 and 4 being exceptions), to be honest. Even T6 had more complicated mechanics than "kite resin puddle to edge. Continue Dps. Rinse. Repeat. Don't die. Done," and that was easily cleared with PUGs back in the day. Getting a Dps group who can meet these simple requests while outputting maximum Dps is like winning the lottery (unless you have a static, that is), and that is the problem.
Also, there is the added issue of nerfed difficulty. Keep in mind that we're comparing Savage Alexander to Normal Coils, and that the Coils were hit with extreme nerfs when they were thrown out into the DF. If you ever ran Second Coil before it was in the DF, you'd know that several of the mechanics were one hit wonders. Didn't turn away for petrify? Dead. Let they cyclops get too close? Dead. Didn't stop attacking during T6 spore move? Dead. Didn't kill a bulb fast enough before it got to growth phase 2? Dead. Miss pretty much any mechanic in T9? Dead. Etc, and this was all considered Normal difficulty.
If you're looking specifically at Tank Busters, than even those have changed. Almost all of the Tank Busters in HW hit hard, sure, but they're basically one and done hits. They did not hit with the same frequency or follow up as the Coils. In T5 you literally did not have enough CD's to mitigate all of the Tank Busters. T9 actually hit at the same frequency, only it was less noticeable because the boss rotation was interrupted more frequently. That being said, Nael followed up every one of her TB's with a second TB that was magic based. You got hit twice. Once the healers figured it out it was nothing to sweat over, but you could say the same for any mech, really. T6? When it was still PF locked you had to Tank swap to handle the frequency of those hits. Not even an option. A single Tank could not do it.
Now, does any of this make Savage somehow easier than the original Coils? Not really no. But I think that the learning curve was higher for the original Coil fights, and there are a lot of sub-par players out there who did not learn those fights thinking they can walk into Savage and make it out okay.