Another reason one might wish to fade instead of just up and leaving or disassociating is to waste their time and resources trying to track you. The up side is that they will waste more time hunting for the time slip (that isn't there) or put you on the Theocraptic Misery "School(??)" for a talk (that you are going to blow off). That wastes time for someone to scramble to fill in the missing assignment. This works better if you have a talkout and blow it off, because that's going to disrupt the whole meeting for that congregation.
Then there are the houndingshepherding calls. Each one of those wastes time to prepare the scriptures to take out of context without putting them in context, in order to hound the person to go back to the meetings. If they go that once or twice but then resume blowing them off, it makes extra work for the hounders. That way, some matter (like a legal issue about some pedophile) will not get addressed, and they might get busted for that.
Some have family ties. Break off too quickly, and you lose them. Others like to waste the hounders' time and energy playing the game. Still others would like to keep their hopes up, only to wait until the Christmas tree goes up and wait for them to catch them. And, there are the ones that are too much of a wuss to disassociate. Not that it's wrong--what is cowardly is continuing to go regularly and seeking "privileges" just because you don't want to make the effort to change. Those are the ones that stand to lose the most.
So, no matter if you are too much of a wuss to officially disassociate or get disfellowshipped, or if you feel like walking out and making a lot of noise on the way out, just remember to count the cost of each method and pick the one that gives you the best outcome. The shame is for the one that stays in even though they know it's wrong, and stays active and regular. No matter how you do it, slowly or all at once, it's best to just get the [a dirty word] out and stay out.