Worth mentioning that Medium is more of an "educational" blog than your typical blogging sites. Ask any engineer, software developer, etc, Medium is where you find explanations for a wide range of topics, up and down the tech tree, and even beyond tech to other science disciplines.

My assumption: in addition to advertising the tech to investors, these Medium posts act as a way to reach a different type of audience: more technically adept ones. Those are usually the ones like FJ and C.AI who could underwrite the tech with their own understanding, then go educate other ambitious but less technically adept ones.