I didn't think before that i may have friends from all over the world. But after using italki as a language aid, I feel that world became a real small village and it's easy to have friends from different countries. And you can also arrange with them to meet if you travel to their countries for any reason or have the courage to visit countries you didn't interested in before . I didn't find other tool can do that even if it's widely used.
In my opinion the main reason for that is because most of people here are very serious about learning and that reflects on their attitude while talking to each other. So you can gain the trust of others, become interested in their lives and concerned with their circumstances.
And on the other hand, there aren't commitments toward the partners like you must have with your closed friends, And the problems are generated from inability to fulfill it.
I think it depends on what you want jack. You can use it only for learning or you can deep your relations and make it real. I had a lot of friends on Facebook when i started to use it I don't know him, But after awhile i began to meet them in different activities and became a friend with some of them.
But I understand your point of view well
A friend online is a quite bizarre and obscure term to describe the relationship among people on an online community. I would not say they are my "friends" because we do not have much to be shared with on basis of language learning.
Personal opinion
