I haven't really seen the argument proposed myself but I can get the reasoning behind it. On PLD I don't think I went into tank stance at all this savage tier, same for the last. Shirk makes threat a non-issue and with how fights are designed, the cooldowns that each tank have are enough to handle the busters. Dungeons and 24 mans would be a challenge to manage without the extra threat tool or mitigation on large pulls so I doubt they'd do it without a major overhaul of each tank's kit.