I agree that there are a lot of "obligation" friends out there - I'm sure we all have them, and despair of them. But other than their rather invalidating presence in and of itself, one of the biggest problems with "obligation" friends is that they fit so nicely into the schemas that many of us have in regard to relationships, ie, "nobody really cares about me or ever could, and anyone who says they do is just pretending...", that it becomes very difficult to accept that there may be actual true friends among them, or to spot those true friends when they are there.
I know I probably falsely categorise people as"obligation" friends sometimes when this is unfair, just because it's what I believe I deserve and all I believe I will ever attract, and I'm sure this is just as hurtful and invalidating for those people as it is for me when the "obligation" friends are so ever present in my world.
There is no end to the struggles I face with relationships, or the ways in which I feel they hurt me, and I hurt others, even as I try so hard not to.
For what it's worth, I always anticipate people taking the "way out" with me too, and almost try to provoke or initiate it, again because it's what feels right to me. So often it comes as a conscious relief when I offer others that "out" and they take it, both because it relieves me of having to battle with my typical social awkwardness, and because it confirms my own beliefs about myself and my relationships, which is a comfort zone, even if an uncomfortable one.
So sad and confusing, all of it.
Maddog