I think it might be
1- since they can see what image you would get out of them when interviewing them.
4- with social media comes a lot of content and if you can see what posts they agree with or even have posted you can easily see if they would offend people.
For the rest, they aren’t really as reliable as an In person interview or 1on1 interview. You can’t really get to know the full story of them but only what they want people to know.