Its not baseless at all. He is the most powerful magician because he is a true god incarnate. E. A. has to downplay himself for you humans. It is honestly quite sickening to me.
He is holding himself back for all the wrong reasons. The Gatekeepers need him, not the other way around. Mr. Kendall too.
They are more powerful then you guys can imagine. They are both true gods in the flesh and you humans treat them like trash. They deserve temples and have humans at their feet. The world would be a much, much better place for it.