It’s not only the Gedolim who state this, however (as has already been mentioned in this thread), the Zohar attributes holiness to the beard and completely forbids it being shaved with anything. The Arizal went one step further and taught not to even touch one’s beard.
Wolf, I would assume your Rav who disagrees with Gedolei Yisroel and ignores the Zohar over shaving also has a basis for this?