Since the introduction of the ladder I've met several '09 players that I was unaware of before. I haven't invited any of them to games yet but they're on my (very short) invite list now.
This game is SO not dead. It's more alive than ever.
Aside from tournaments, I haven't joined any open games since being a member. Which is to say that I get invited to enough games not to have to go looking for them. But I don't play real-time games anymore, so I guess that just means I have made it onto enough people's invite lists in the several months that I've played here. I suppose it would be different for a newer person.
Fizzer is the person to ask about how many new members there are and how often they're created.
I can't imagine that there is any kind of deliberate segregation going on.
I have created a game with no prerequisites just for new players to join.
Here's the URL: http://warlight.net/MultiPlayer.aspx?GameID=1230067
It's a pretty big game but I wanted a lot of people to join. Hopefully, it will convince new players that this game rocks!