I get this question a lot! Mostly from experienced writers who know the value of writing partners and groups, but due to travel or family life or living too far from a city, they can't join a "normal" group.
Writer's groups and writing partners provide a couple of benefits to a writer's life. Writing is a solitary thing, and it's easy to get a little nutso when you've been on your laptop, deep in your story, for hours without interacting with another human. Even a virtual interaction provides a way back to normal life, perspective on what you've been doing (even if it's a universe in itself), and ideally, some feedback along the way.