Harsh Mistress is one of my all time favorite books as well. As for the AI, Heinlein wrote that in an era long before the whole cyberpunk genre was conceived, and certainly before it started becoming a real-life thing that we are all living through currently. Things like social media simply weren't on his radar scope as a story writer.
Before William Gibson, AI was generally thought of in terms of simple artificial beings. HAL-9000, Robbie the Robot, C3PO, etc. Even Skynet seemed to be made up of stand-alone robots, and was thought of as some "thing" you could physically fight, or even have a conversation with, something which many of the franchise's characters do in the various sequels and TV show. You can't reason with or have a fight with Facebook's algorithms, and you can't resist the way google has changed the world, like it or not.
I saw the Starship Troopers film before I read the book, and I thought it was an awful movie. It was like the guy was trying to recapture the magic of his satirical Robocop movie and failed. Then I read the book shortly thereafter and hated the movie even more; the film was made by somebody who obviously had no respect for the deceased author and chose to use his own story to ridicule him.
Worse, the film left out the coolest thing in the book: powered armor suits.
At least The Expanse has those!
