I assume approaching his guests as a layman allows his viewers to scratch the surface of tech/science/topics potentially inaccessible to people outside of the normal scope.
I like Lex, he's very open and wears his heart on his sleeve, he gets good answers sometimes because he's fearless with the questions he asks. His first intrview with Jim Keller is my fav ever and changed my life perspective after some of the gold Lex gets out of him. But yeah his programming knowledge seems very limited, same level as most Machine Learning engineers with science backgrounds.