Ah, I see. The thing is though, the people that were maximizing back in the days of scob and fcob are still maximizing now, and you carry that with you on the back of your skill as a player, and it transcends gear/stats. Even in coil, regardless of if you had to put on more fending gear, you still maximized your raid awareness and GCD usage to pump out as much DPS as you could in the confines of that. The assumption that tanks were just half-assing their play back then is misleading and a little insulting to tanks that were... i dunno... trying? And you did have to try at first unless you were clearing this in full i120-i130 gear. T12 is a great example of this. How easy people say T12 was is extremely telling of how geared they were when they cleared it. The Bennu DPS check was no joke.
The fact that maximizing before (like in bcob) meant mitigation and maximizing now means DPS does not make one inherently more skillful than the other. It just means "Woo! Big numbers on the screen!"
I do not think you have anything to be scared of with what SE appears to be planning. What I'm hoping is that they make it so that there is not a choice between gearsets with one being fundamentally better than the other. Who knows what they'll do. They might lock tanks into fending gear but give tank weapons a crap-ton more weapon damage or something. Your DPS might go down a bit from what it was in full slaying, but still WAY more than the equivalent in full fending, AND you'll have more HP, which means healers will get more of a chance to maximize their DPS as well, and we won't have this stigma in the game attached to our gear. Your skill as a player still matters and always does no matter what gear you are wearing, and lets be real here, most of the stunts us tanks pull in slaying gear ride on the skill of our healers, as much, if not more than our own. Yet we talk about it with such pride which I just do. not. under. stand. Its like check out my insane skills as I click this slaying gear onto my character sheet! Its a fallacy to assume a player cannot maximize their actual in-combat play based on limitations of gear.