To me the argument makes more sense in reverse:

Gitflow solves a problem few teams actually have. Throwing away a working (simpler) process of having a single trunk when there's no real benefit doesn't seem like a great idea.

It seems to me that Gitflow just adds a lot of ceremony of keeping multiple branches somewhat in sync through merges left and right.

I'm fine with the argument of keeping existing processes because they work, whatever they are.