Rank-restricted boards where?

It's impossible to have any actual discussion about game play when 95% of boards users are below Diamond, and inevitably flood threads with posts like 'lol i built ad brand and stomped, your argument is invalid.'

Right now, I'm only interested in what other Diamond players think about the pre-season changes, but I can't sift through the posts by unknowledgeable/unskilled players. Rank-restricted boards are really needed.