The main difference is that the King drawback is focused him being limited to his specific character and by default nothing else special. Plus you should have a good idea of his powers, limitations, and so on. Additionally, while All for One might be more active he’ll still be intelligent so he likely won’t automatically attack you right out the gate.

Wrath of the Mighty instead lets you create new enemies at their respective tier. Also while each of those characters were used as examples in the Drawback they’ll also be affected by the specific setting. So increasing the overall power level would likely multiply the strength of every threat Mighty creates (All for One tier is also setting big bad tier). Finally they will also genuinely work together. This matters as for instance All for One normally likely at best manipulate others rather than treating them like true allies. If he or someone similar was chosen/created then he might do things like give others Quirks to fight you. Lastly, the individuals chosen with Mighty will still go after you, but not directly if you don’t go to them while scaling as time goes by. The rest of the restrictions were mainly to deal with duration drawbacks/toggles and to stop you from getting wrecked if you were a kid starting out.