>>49457167From my understanding the argument is whether dynamax outclasses megas in terms of power and brokenness.
Here are some stats I found in regards to natdex ag.
Considering the fact that Yveltal (and Necrozma-Dusk-Mane) seems to be more popular than the most broken mega, I would assume to be true.
Dynamax as a whole got banned, while megas were more case by case.