I suppose it's because, in a way, you aren't any different to me than the friends I have that live in other countries. Just because I've never seen you face to face, doesn't make you any less real to me than those friends I can't see for years due to distance.
I think there's also a depth to the friendships we make online because we tend to talk quite openly about our lives, our feelings, worries & joys in a way that we don't always in person.
Funnily enough, you look pretty much exactly how I pictured you in my mind. Now, I have a brain like a sieve, so you may have posted a pic before and that's why my image of you is so accurate. I'm not sure?!
I would give you my home address, phone number, spare room etc without hesitation. As I would with a list of MNers who I feel certain are genuine.
I'm pretty sure too, that if I needed you, you'd be there for me, as much as you were able.
If you mean specifically why you, I guess it's because I have got to know you over the years and I like you. I also really feel for you with the things you have been through and I was really, really happy and scared when you went to meet ZombieLad. I was worried about you when you went haring off in the middle of the night on your mercy dash and I could kick your twathead ex to to the moon for you.
I'm not sure if any of that answers your question.