not sure how you guys say you can do 70-80 with just the MSQ (or until 78-79 as some said). I went into ShB at 71, so 1 level "ahead". The initial Ali / Alphi questlines took me to almost 72 (the are lvl 70 so you assume they would take one to 71), but then the 71-72 bracket is literally just 2 MSQs, the dungeon quest and then the conclusion of what happens there. Two MSQs would take noone from 71 to 72.

No, the M72 MSQ bracket is just 8 quests until you need 73 for the next one. 8 quests at 540k xp is roughly 5-6mill xp, and you need 15.5mill to go from 72 to 73.

So yeah, you absolutely cannot just do the MSQ in ShB.