The author was a prominent talmid chacham who founded the Michlalah in Jerusalem. I someone disagrees, so he can also write a sefer. Notthat I am comparing, c”v, but Moreh Nevuchim was burned and all of Ramchal’s books were banned.
As for haskamot, please cite where Ramban says this. It would apply to all sefarim today as no one gives a real haskama. They give berachot. BTW, the mekubbalim starting with the Zohar say that Hashem runs the world through intermediaries. The Jewish people in Eretz Yisrael are an exception. The Rivash objected to the idea of sefirot (Responsa 157) but there are other legitimate opinions.