Yeah but if SE intended for tanks to use nothing but tank stance, why would Shield Oath not be at 30, or even 15 like I mentioned? Why even have Sword Oath before 50 if there's no content requiring 2 tanks before that point?
And SB release was just a mess for many classes, I think it's safe to say the devs did a lot of experimenting that didn't pan out quite like how they envisioned it.