Yeah!!!! It blew my mind (haha) too. And nope! not a handicap, just a different way of experiencing their mind. Some of them even think we're the ones with the handicap, having a voice chattering in our heads all day. Here's a couple of articles you might enjoy!

https://www.iflscience.com/people-with-no-internal-monologue-explain-what-its-like-in-their-head-57739

https://www.theguardian.com/science/2021/oct/25/the-last-great-mystery-of-the-mind-meet-the-people-who-have-unusual-or-non-existent-inner-voices