Re: "Given that Twitter serves as the de facto public town square…"
The Register is not quite Radio4
Personally, I've been pleasantly surprised at the resilience and development of commentary on El Reg. While there are plenty of oldtimers, it seems there is reasonable supply of new people with their own ideas. There are areas of broad agreement but, politics aside, I think there are few areas where the "my way or the highway" mentality of many echo chambers. And even when politics breaks through, it's generally (not always), possible to accept differing opinions may be valid. Of course, this does indicate some degree of socio-economic self-selection, but that's true for all media. And I suspect the moderators are kept busy.
And, The Register, manages to provide a degree of balance through the bootnotes, etc.