I began my fade inadvertently when I became very ill for a long while. There had been a number of problems in our congregation anyway, and now I had the time to identify questions and doubts that had never been answered. Finding the answers to these questions was a 'revelation'! What a sham I had been involved with for all of my life!
Now, several years later, I've maintained my relationships with a very few friends who are still JWs, and I still have family in. But since making the decision last year that this was not the Truth, I can see that the time is coming when my cover will be blown. This year will be the first that I will not attend the Memorial and just last night my friend let me know the date and told me she wanted me to come. I was caught off guard and didn't know what to say, and she asked me why I wasn't saying anything, letting me know she is going to push this. I told her that it felt pretty hypocritical to attend that one meeting after not attending any others, but she didn't buy it.
When it comes up again I still don't know what to say to her, so the end may be near. It might just be a relief.
So I think the reason most people fade instead of DAing is because they want to keep their relationships with friends and family.