It's not that they aren't familiar with the topic, it's that a lot of them aren't interesting people who add nothing to the podcast. The Zuckerberg episodes are good examples of episodes that are completely ruined by the choice of guests, it's like being back in highschool with a bunch of yelling teenagers. McAfee too, with the obnoxious and constant attempts at humor that never hits the mark.

While other guests have interesting input even when they don't know anything about the subject beforehand, because they're not entirely void of any interesting personality traits or thoughts.

I'm guessing it doesn't matter if I spell it out for you. The fanbase somehow seems to think some of these guests are a good listen. Weird shit.