My guess is that those who have access to F are not likely to be scouring the net on sites like here for ways to go... So most of us don't have the street skills to get reliable sources of F. I know that if I did, it would be sitting in my drawer and I'd feel a little better about going about my life knowing I had a painless quick way out if it came to it. There was a time I was seriously wracking my brains for ways to get F, but I know I don't have it in me to approach the people I would need to to get it.
In the last few years, things have gotten bad out there for a lot of people. In most large cities, there are spots where you'll see people who clearly know where to get that stuff. I've thought about it recently, but I am extremely "street dumb" so I'm quite sure I will get myself into more trouble than I need if I try. All to say that I'm open to finding a source but sadly it's harder for some of us to get than SN, which I have.