Democracy doesn't happen in conventions

I was reading electablog the just now and he commented on how going to the Democratic convention opened his eyes on how Democracy works.
I've got news for anybody who thinks political conventions are a part of the democratic process, they are clearly not any more. Maybe at one time nomination conventions were meant to chose a candidate for the national political parties but that time has passed. Candidates are chosen well before the actual convention and conventions merely rubber stamp the party's preferred candidate. Conventions are now an impediment to the democratic process because they provide the preferred candidate a chance to coopt his former primary opponents messages and silence any critics within the party thus squashing any serious dialogue.
What's worse is that conventions are vehicles of a two party system that excludes any and all others. We essentially have two state mandated political parties. Conventions aren't about democracy, Conventions are a tool of the political establishment to control the voting public. The entire thing is a giant sham.