Hey, I was looking around forums in fields different then my own (Biology) and I agree with most people on here. Money is no doubt a big factor, flying people out and hosting them for a weekend, maybe even longer sometimes does cost a pretty penny. Also, someone said Soc does not have POIs working directly with grad students. In the sciences this is basically what it is. You find a lab whose research matches your own and apply to join said lab. Personality fit is a huge factor in my field, a lab (professor, other grad students, post-docs, techs) becomes an extended family of sorts and everyone I talked to (grad students, and professors) have told me I will not get into grad school without at least a phone interview. The best is a face-to-face.
I hope this helps. Good luck everyone!