Why can't we think for ourself?

With epic gear dropping like candy and detailed guides and videos there should be no reason any moderately skilled group couldn't do Sarth 3D. Zergin Sarth requires next to no strategy, little movement and nothing special from any of the participants. That is except for the Tenebron taunt and run at the end.

Up until last night I had never had a go at it. But as a guild group for it was put together and they needed a tank I joined in. Before we went at it we had a small talk about the strategy, or lack there off. Everybody had read the same guides and seen the same video, but as we were lacking the recommended feral druid to handle Tenebron they decided to skip that part and just ignore the enrage. Being my usual easygoing self I didn't press the point on getting Tene off me for the enrage and we went in to wipe repeatedly.

After the 4 or 5 wipe people was starting to realize that we just weren't getting anywhere. Each wipe was the same with Tenebron enraging when Sarth got to 20%, me poping DP, when DP finished taking one hit then LoH and then dying 2 hits later before the rest of the raid went down. With no Guardian spirit or Pain suppresion, the druid healer just couldn't keep me up for the time it took us to do the last 20%.

What should we do? Complain that we needed a feral druid to make it? Indeed some of the group did just that. Or dear to think just a little beyond the what the guide said? Well some of us did that to. Seeing as we had a DK we just asked him to get max distance from Tenebron, taunt him at 25% and run like crazy. Of course he couldn't out run Tene, like a druid would have. But he might be able to buy us the time we needed. Of we went and down Sarth came.

Why didn't we do that from the start? We knew Tenebron was gona enrage. We knew he needed to be taunted of the tank. In other cases we have been able to quickly come up with strategies to do hard encounters. Why did we wipe repeatedly on something like this that should have been a easy run?

Only reason I can think of is that we all read the guides and the 'use feral druid' of the guides locked us into that thinking. Are people that easily locked into a way of thinking? Are you?