Even granting the premise (LW as the highest-level general discussion forum on the internet), the question remains of how that compares to all the other venues out there. And, honestly, it still doesn't come close to what I can get at a good academic conference, or even over dinner with colleagues. Your competition isn't Reddit, it's all the places where elites (however constructed) are already hanging out and minimizing noise. For this, focus is a feature, not a bug.

Even for the internet, you pointed out the value of more focused forums (which is where I'll generally go for higher level discussion). But I don't consider this place "relatively-general-interest". I come here when I want FAI or rationality discussions. So, one suggestion would be to consider that your goal of strengthening the general interest aspect might be ignoring your strengths.