All flight sim sites have been asked to join, some have some have not. The sites listed that show a '1' under 'in' have not finished signing-up and not included the voting banner/graphic on their web pages. If you read Garry's announcement the Top 100 is meant as an aid to people looking to find resources and is not a popularity contest. I think it's a great idea, I also believe there are more than 100 resource sites that should be on the list.
Personally I visit many different sites and appreciate the people who give their time freely to this hobby.
Variety is the spice of life and there are a bunch of good sites that need to be known and frequented. There are hidden treasures if you go out and look around.
Garry has given much to the community, he is well respected and is just trying to help community members so why not support his effort and sign up, what is there to lose?