The reality is that people who choose to slow down meeting attendance and service when fading will come under a great deal of pressure from well meaning family and friends, and some people are just not in a position to be open about their feelings. When you only choices are to be completely honest and lose your family or to tell a minor fib, I am not going to condemn anyone for choosing the lesser of two evils.
This is a short term tactic, but it can be very helpful during the transition from full believer to inactive JW. It can give the person time to become more sure of their feelings, to get their family used to the idea that they don't want to attend meetings and to get the elders off their backs. Yes, it would be great if everyone could be completely open and honest about their reasons for leaving, but that isn't the reality for most people.