Stoicism and many other Greek philosophies were much deeper than just thinking different ideas and concept in abstract and writing them down.

Stoic philosopher was someone who was living his life according to stoic philosophy. To learn philosophy and to become a philosopher was to enter training program where you live with the teacher and internalize the philosophy as way of life.

Why would anyone read books about philosophy of bodybuilding and how to lift weights for years if they are not going go to go to gym and actually train? In a same way, you can't really become a Stoic philosopher by reading the books.

Kinda wondering why the geniuses who surround him haven’t just made endless tapes of interesting discussions and then had him ghost-written up

The article states he's perfectionist. He probably wouldn't be OK with that.

Same for Saussure, whose most-read work was a compilation of his notes by his students and colleagues after his death.

Socrates/Plato as well.

More contemporarily, George Herbert Mead's influence is based mainly on his transcribed lectures contained in Man, Self and Society. Mead wrote a good deal during his lifetime, but always relatively short pieces that he never bothered to compile together into books or programmatic statements of his philosophical position.

(as alluded to in the article.)