Nothing I'm aware of, but I think part of why most realtors use Facebook and Instagram instead of something else is that their intent is to bring-in customers,

Nothing I'm aware of, but I think part of why most realtors use Facebook and Instagram instead of something else is that their intent is to bring-in customers, so they need to be not where other realtors (their competition for business) hang out, but where people who need relators hang out, and where the friction required to engage with these non-realtors is low.