Well what I think is that people that you meet online and been talking too for years is more a friend than someone you've met for 2-3 days, that's more of an acquaintance, but there is a certain sense of anonymity and coldness that you get from people online then people you can actually see, like their mannerisms, how they look, the way they talk. You can get so many false thoughts of a person from just text, you can never really know someone ti'll you have heard them or seen them, it's just not possible.
But on the other hand the text is more a window to a person than people think. You can still have a sense of who they are and what their mind set is on things if you have chatted long enough with this person. You can still call them your friend even though you have never actually seen them, sure you have to trust what they say but you will still develop a bond if you have interacted for that long, and any charade that they might have tried to keep up would eventually crumble after that amount of time.
Also by that amount you must be able to trust them for they have stayed by you side and if you trust what they say then they must trust with what you say if they keep coming back and you keep talking to them, its obvious if you have stayed that long then you see something good with that person's personality and in many ways the internet gives you a better experience because you can meet and interact with people that not only have the same interest as you to be on there but as well the only thing you can know from them is their personality since you have no idea what they look or sound like, you might have never seen them in real life because of the way they might look like or walk or talk since your mind automatically assumes certain things about a person.
And this was supposed to be a short answer :P