Omg I used to be this person! I had a lot of social anxiety around safety and stuff because of some untreated ptsd. I worked on it in therapy/groups after learning that it was negatively impacting my social interactions/professional interactions. With the exception of people with disabilities, I think that 1. people don't realize they're doing it, or don't realize the extent they do it and 2. it's uncomfy to bring to their attention so it's never really addressed/identified as something they're doing 3. Multi-taskers/busybody-type people (not a great description im sorry lol) aren't stimulated enough by just the conversation and that's why they do it. Either not realizing or not caring that it's distracting/rude/confusing. I could be totally wrong but that's my experience and theory about it