There was only one post by Lack on this... and it was pretty general at best. I quoted it once, but I can't find it now. The concern seemed to be that this would make it too difficult to gain points for new players, who may be skilled but simply start at 1000, which is somewhat below the median score I think. Anyway, its a fair concern; if done wrong, this could kill the ability to attract new players.
Imagine that you can limit that only Briggadiers can join your games. That would mean you would be cut off from challenge by most of the site, and even though people do that a bit now with PM's and private games, making that phenomenon public would not be good for morale. Every search would bring back tons of games that were "rank blocked" if you tried to play someone with a higher rank.
In order to preserve the "climb the ladder" model, I say staunchly that the way this needs to be implemented is in a tier system. And the cutoff point for any tier that someone can select has to be BELOW, but not too much below, their own current rank. i.e., colonels should not be able to limit to colonels, but only perhaps captains and higher. Captains should not be able to limit to captains, but perhaps sergeants and higher. anyone 1000 and below would not have the option to limit games for obvious reasons.
Perhaps since lack's original post was a while back, and now the site shows that it is creaking at the seams, maybe growing the player base should no longer be a top priority. I'd like to think it's still important though. I'll try to find lack's old post ...
Here we go... check the last one. It's from back in 2006.