Church services require people to be in the same place at the same time, for the same purpose.

Few other activities gather the same people regularly. I can immediately think of narrow social networks (like obscure subreddits), and online games, though.

Although those activities lack the factor of physical presence. For a lot of people in modern society the only time they are around others is at work or in public places neither of which have a primary focus on community and fellowship like a church congregation. We desperately need to add more community gatherings that don't exclude people based on skill or ability.

>require people to be in the same place at the same time, for the same purpose.

Otherwise known as the most effective way to build friendships.

World of Warcraft raids are the only one

Isn't the potential connection obvious? If you remove the main source of community and making friendships outside school/college and your workplace, that could definitely lead to loneliness.