It's worth noting that the enrage timer on most fights doesn't go much past ten minutes. Saving "a few minutes" represents bypassing a significant portion of the fight.

I know this has been done to death before, but defensive stance usage doesn't have much to do with healer dps in boss fights. If an auto hits for 5k raw damage, the stance mitigates 1k. Your healer doesn't manually heal that. It comes from regens and the fairy. You're sacrificing 15-25% of your damage output for no benefit. In fact, if you look at some optimised Faust runs even pre-echo, neither healer is actually casting heals. It's all done through clever use of cooldowns and instant casts. Some of the optimisation tricks that they do are pretty amazing, really.

Your damage output as a tank isn't really a test of your rotation. Tank rotations tend to be relatively simple in comparison to your average dps job. Tank dps depends on your defensive stance usage because it illustrates how well you understand the damage pattern in a fight. If you don't understand how much damage goes out and when, then you're forced to play more defensively, and your damage output suffers.

Toxicity has nothing to do with the meta. You can find groups who are happy for you to sit in defensive stance for the entirety of the fight. The problem is, they may not live up to your expectations in terms of skill. Perhaps they may struggle to get a clear, or not clear at all. Toxicity only happens when there's a mismatch in effort, skill, and expectations. If you want to set your expectations for others higher, then you should expect to be held to a higher standard yourself.