Not all armys are here for the awards (although well deserved).
The reason why I always look forward for their attendance is because their MMA performances have been historical/for the books since 2018. I was a casual fan in late 2018 but then MMA happened and I finally understood why so many people liked them.
Ofc, their MMA and MAMA stages are always the best. Those stages usually mark the beginning of award show seasons. But what can we do? They have other schedules in the US on the 4th Dec (KST). Hoping for some performances aint wrong but when we already know that they wont be available in S.Kor at that time is basically asking yourself for a dissappointment.
And it seems like they high likely wont attend MAMA as well (maybe they still have other schedules that we dont know about in the US yet) + even if they manage to fly back to S.Kor on 5-10th, S.kor are still imposing 10 days quarantine (or Active monitoring) period to their korean nationals flying in. They prob wont be able to attend MAMA bcos of that. That's why MAMA announced SWF, W1 and Ed as their headliner acts.