Don't forget that those that have left may still have significant other reasons for checking in every now and then, eg family, friends involved in the military or they may still give some of their spare time to the military, ATC, AEF or reserves.
I have seen that some who have left have also been able to pass on valuable information to those who are leaving or those considering it. I'm talking about licencing issues, logbooks, cvs etc. Certainly helped me when I was on my way out. There is a lot of good experience that has left the mil, in this day and age can those that are still in afford to exclude the opportunity of perhaps still benefitting from some of it? If you don't like someones attitude or ideas file them on the pending tray
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I agree that you should be careful about always thinking about WIWO... or WIWI..., things have changed and will continue to change, but many of us still have a very good idea as to what it is currently like in the mil.