the distinguishing factor is whether you’re losing access to “certain individuals or communities” that you cannot access otherwise. When people leave a digital space, they tend to “channel communication through other means. They use texting more. They set up group chats,” according to Hall. And if they don’t (or can’t) find other means to connect with those people, that’s when they tend to feel lonelier offline.>

Seems to me like people get a sense of community with social media and if they can't replace that void when they quit then they are more prone to get lonely.